Role of adenosine A2a receptor in cancers and autoimmune diseases

Neoantigen mRNA vaccines and A2A receptor antagonism: A strategy to enhance T cell immunity

Although neo-antigen mRNA vaccines are promising for personalized cancer therapy, their effectiveness is often limited by the immunosuppressive tumor microenvironment (TME). The adenosine A2A receptor (A2AR) inhibits dendritic cell (DC) function and weakens antitumor T cell responses through hypoxia-driven mechanisms within the TME. This review explores a novel strategy combining neo-antigen mRNA vaccines with A2AR antagonists (A2ARi). By targeting A2AR, this approach reduces TME-induced immunosuppression, enhances DC activation, and improves neo-antigen presentation. The review also discusses lipid nanoparticles (LNPs) to co-deliver A2ARi and mRNA vaccines, optimizing their effectiveness. The integration of neo-antigen mRNA-LNPs with A2ARi modulation offers a promising strategy to overcome immunosuppression, stimulate DC activation, and achieve precise anti-tumor responses with minimal off-target effects. This synergy represents significant progress in cancer immunotherapy, advancing the potential for personalized neoantigen therapies.

Coffee consumption and risk of multiple sclerosis: A systematic review and meta-analysis

BACKGROUND

Multiple Sclerosis (MS) is an immune-mediated disease with miscellaneous etiological origins. Given caffeine's neuroprotective and anti-inflammatory attributes and its potential influence on MS risk, and to address the conflict in the clinical evidence, this study aims to comprehensively review the existing literature on the association between coffee consumption and the risk of MS.

METHODS

Following the PRISMA 2020 guidelines, a systematic search in PubMed, Scopus, Web of Science, and Embase for the studies published up to January 2024 was conducted. Studies that assessed the relationship between coffee intake and the risk of MS were included, and reviews, case reports, non-English papers, in vitro and animal studies, and conference abstracts were excluded. The risk of bias was assessed using the JBI checklists, and meta-analyses were conducted based on odds ratio (OR) using the fourth version of CMA software.

RESULTS

Out of 604 initial records, 10 observational studies with 19,430 participants met the inclusion criteria. The included case-control studies showed an overall high quality. Meta-analysis revealed a reduction in MS development in coffee consumers both before (OR: 0.66; 95 % CI: 0.49-0.90; p-value: 0.008; I2: 89.65 %; p-value for heterogeneity<0.001) and after adjustment for possible confounders (adjusted OR: 0.42; 95 % CI: 0.20-0.90; p-value: 0.025; I2: 89.65 l; p-value for heterogeneity<0.001).

CONCLUSION

Coffee consumption, may decrease the risk of MS; however, further well-designed prospective studies are required to ascertain this association. PROSPERO registration number: CRD42023484298.

Design, development and evaluation of a tritium-labeled radiotracer for ecto-5'-nucleotidase (CD73) - A versatile research tool and diagnostic agent for personalized medicine

Ecto-5'-nucleotidase (CD73) is the main enzyme that catalyzes the hydrolysis of extracellular AMP to produce anti-inflammatory, immunosuppressive adenosine. Many tumor cells over-express ectonucleotidases accumulating adenosine in the tumor microenvironment, which promotes tumor growth, metastasis, angiogenesis, and immune escape. CD73 is upregulated in inflammation, and possesses potential as a biomarker and as a novel drug target for inflammatory diseases and cancer immunotherapy. New, metabolically stable N6-disubstituted adenosine-5'-diphosphate analogs were synthesized providing a basis for the design and preparation of the CD73-selective radioligand [3H]PSB-17230 by catalytic hydrogenation of a propargyl-substituted precursor. It showed high, pico- to low nanomolar affinity for human, rat and mouse CD73, slow dissociation kinetics, negligible non-specific binding, and high selectivity, as confirmed by studies on an inactive CD73 mutant and CD73 knockout cells. A high-resolution co-crystal structure (2.35 Å) of PSB-17230 with human CD73 elucidated its binding interactions. Radioligand binding was employed to characterize competitive CD73 inhibitors and to study expression levels of the enzyme in tissues and tumor cell lines of different species. Moreover, [3H]PSB-17230 was employed in autoradiography studies to determine CD73 expression in healthy and diseased mouse and human tissues. Significant upregulation of CD73 was observed in a mouse asthma model and in kidney cancer biopsies as compared to healthy controls. [3H]PSB-17230 represents a high-affinity tracer which is anticipated to find broad application in drug screening, preclinical studies, and for diagnostic purposes in inflammation and cancer, enabling drug monitoring and targeted therapies.

Accumulation of CD38 in Hybrid Epithelial/Mesenchymal Cells Promotes Immune Remodeling and Metastasis in Breast Cancer

Triple-negative breast cancer (TNBC) is a highly metastatic subtype of breast cancer. The epithelial-to-mesenchymal transition is a nonbinary process in the metastatic cascade that generates tumor cells with both epithelial and mesenchymal traits known as hybrid EM cells. Recent studies have elucidated the enhanced metastatic potential of cancers featuring the hybrid EM phenotype, highlighting the need to uncover molecular drivers and targetable vulnerabilities of the hybrid EM state. Here, we discovered that hybrid EM breast tumors are enriched in CD38, an immunosuppressive molecule associated with worse clinical outcomes in liquid malignancies. Altering CD38 expression in tumor cell impacted migratory, invasive, and metastatic capabilities of hybrid EM cells. Abrogation of CD38 expression stimulated an antitumor immune response, thereby preventing the generation of an immunosuppressive microenvironment in hybrid EM tumors. CD38 levels positively correlated with PD-L1 expression in samples from patients with TNBC. Moreover, targeting CD38 potentiated the activity of anti-PD-L1, eliciting strong antitumor immunity, with reduced tumor growth in hybrid EM models. Overall, this research exposes upregulation of CD38 as a specific survival strategy utilized by hybrid EM breast tumors to suppress immune cell activity and sustain metastasis, with strong implications in other carcinomas that have hybrid EM properties. Significance: Hybrid cells co-featuring epithelial and mesenchymal traits in triple-negative breast cancer express elevated levels of CD38 to induce immunosuppression and metastasis, indicating CD38 inhibition as potential strategy for treating breast cancer.

Immune Cell Interactions and Immune Checkpoints in the Tumor Microenvironment of Gastric Cancer

Gastric cancer (GC) ranks as the fifth most prevalent malignant neoplasm globally, with an increased death rate despite recent advancements in research and therapeutic options. Different molecular subtypes of GC have distinct interactions with the immune system, impacting the tumor microenvironment (TME), prognosis, and reaction to immunotherapy. Tumor-infiltrating lymphocytes (TILs) in the TME are crucial for preventing tumor growth and metastasis, as evidenced by research showing that patients with GC who have a significant density of TILs have better survival rates. But cancer cells have evolved a variety of mechanisms to evade immune surveillance, both sialic acid-binding immunoglobulin-like lectin 15 (Siglec-15) and Programmed Death-Ligand 1 (PD-L1) playing a pivotal role in the development of an immunosuppressive TME. They prevent T cell activation and proliferation resulting in a decrease in the immune system's capacity to recognize and eliminate malignant cells. These immune checkpoint molecules function via different but complementary mechanisms, the expression of Siglec-15 being mutually exclusive with PD-L1 and, therefore, providing a different therapeutic approach. The review explores how TILs affect tumor growth and patient outcomes in GC, with particular emphasis on their interactions within the TME and potential targeting of the PD-L1 and Siglec-15 pathways for immunotherapy.

Metabolic Signaling in the Tumor Microenvironment

Cancer cells must reprogram their metabolism to sustain rapid growth. This is accomplished in part by switching to aerobic glycolysis, uncoupling glucose from mitochondrial metabolism, and performing anaplerosis via alternative carbon sources to replenish intermediates of the tricarboxylic acid (TCA) cycle and sustain oxidative phosphorylation (OXPHOS). While this metabolic program produces adequate biosynthetic intermediates, reducing agents, ATP, and epigenetic remodeling cofactors necessary to sustain growth, it also produces large amounts of byproducts that can generate a hostile tumor microenvironment (TME) characterized by low pH, redox stress, and poor oxygenation. In recent years, the focus of cancer metabolic research has shifted from the regulation and utilization of cancer cell-intrinsic pathways to studying how the metabolic landscape of the tumor affects the anti-tumor immune response. Recent discoveries point to the role that secreted metabolites within the TME play in crosstalk between tumor cell types to promote tumorigenesis and hinder the anti-tumor immune response. In this review, we will explore how crosstalk between metabolites of cancer cells, immune cells, and stromal cells drives tumorigenesis and what effects the competition for resources and metabolic crosstalk has on immune cell function.

Polydeoxyribonucleotide enhances the bioactivities of stem cells from human exfoliated deciduous teeth through Akt activation

Although numerous approaches have emerged to address the challenges of critical limb ischemia (CLI), their clinical trials have proven elusive. Stem cell therapy has been utilized for CLI; however, its efficacy is limited, resulting in low survival rates in patients. Here, we investigated the impact of polydeoxyribonucleotide (PDRN) on the bioactivities of stem cells derived from human exfoliated deciduous teeth (SHED) against oxidative stress. PDRN treatment increased the proliferation, migration, antioxidant properties, and mitochondrial respiration of SHED. These beneficial effects were regulated by Akt activation. Through a murine hindlimb ischemia model, PDRN treatment demonstrated augmented the survival and proliferation of transplanted SHED at ischemic injury sites, whereas the inhibition of Akt suppressed these effects. Our findings revealed that PDRN promoted the therapeutic potential of SHED via Akt phosphorylation, suggesting PDRN-primed SHED as promising candidates for the development of novel stem cell therapeutics.

Biomaterials' enhancement of immunotherapy for breast cancer by targeting functional cells in the tumor micro-environment

Immunotherapy for breast cancer is now being considered clinically, and more recently, the number of investigations aimed specifically at nano-biomaterials-assisted immunotherapy for breast cancer treatment is growing. Alterations of the breast cancer micro-environment can play a critical role in anti-tumor immunity and cancer development, progression and metastasis. The improvement and rearrangement of tumor micro-environment (TME) may enhance the permeability of anti-tumor drugs. Therefore, targeting the TME is also an ideal and promising option during the selection of effective nano-biomaterial-based immuno-therapeutic strategies excepted for targeting intrinsic resistant mechanisms of the breast tumor. Although nano-biomaterials designed to specifically release loaded anti-tumor drugs in response to tumor hypoxia and low pH conditions have shown promises and the diversity of the TME components also supports a broad targeting potential for anti-tumor drug designs, yet the applications of nano-biomaterials for targeting immunosuppressive cells/immune cells in the TME for improving the breast cancer treating outcomes, have scarcely been addressed in a scientific review. This review provides a thorough discussion for the application of the different forms of nano-biomaterials, as carrier vehicles for breast cancer immunotherapy, targeting specific types of immune cells in the breast tumor microenvironment. In parallel, the paper provides a critical analysis of current advances/challenges with leading nano-biomaterial-mediated breast cancer immunotherapeutic strategies. The current review is timely and important to the cancer research field and will provide a critical tool for nano-biomaterial design and research groups pushing the clinical translation of new nano-biomaterial-based immuno-strategies targeting breast cancer TME, to further open new avenues for the understanding, prevention, diagnosis and treatment of breast cancer, as well as other cancer types.

The Effects of Caffeine on Blood Platelets and the Cardiovascular System through Adenosine Receptors

Caffeine is the most popular and widely consumed behaviourally active substance in the world. This review describes the influence of caffeine on the cardiovascular system, with a special focus on blood platelets. For many years, caffeine was thought to have a negative effect on the cardiovascular system mainly due to increasing blood pressure. However, more recent data suggest that habitual caffeine consumption may reduce the risk of cardiovascular disease and hypertension. This could be a significant finding as cardiovascular disease is the leading cause of death worldwide. Caffeine is known to inhibit A1 adenosine receptors, through which it is believed to modulate inter alia coronary blood flow, total peripheral resistance, diuresis, and heart rate. It has been shown that coffee possesses antiplatelet activity, but depending on the dose and the term of its use, caffeine may stimulate or inhibit platelet reactivity. Also, chronic exposure to caffeine may sensitize or upregulate the adenosine receptors in platelets causing increased cAMP accumulation and anti-aggregatory effects and decrease calcium levels elicited by AR agonists. The search for new, selective, and safe AR agonists is one of the new strategies for improving antiplatelet therapy involving targeting multiple pathways of platelet activation. Therefore, this review examines the AR-dependent impact of caffeine on blood platelets in the presence of adenosine receptor agonists.

The impacts of obesity in rheumatoid arthritis and insights into therapeutic purinergic modulation

Rheumatoid Arthritis (RA) is an autoimmune condition responsible for the impairment of synovia and joints, endangering the functionality of individuals and contributing to mortality. Currently, obesity is increasing worldwide, and recent studies have suggested an association between such condition and RA. In this sense, obese individuals present a lower capacity for achieving remission and present more intense symptoms of the disease, demonstrating a link between both disorders. Different studies aim to understand the possible connection between the conditions; however, few is known in this sense. Therefore, knowing that obesity can alter the activity of multiple body systems, this work's objective is to evaluate the main modifications caused by obesity, which can be linked to the pathophysiology of RA, highlighting as relevant topics obesity's negative impact triggering systemic inflammation, intestinal dysbiosis, endocrine disbalances. Furthermore, the relationship between oxidative stress and obesity also deserves to be highlighted, considering the influence of reactive oxygen species (ROS) accumulation in RA exacerbation. Additionally, many of those characteristics influenced by obesity, along with the classic peculiarities of RA pathophysiology, can also be associated with purinergic signaling. Hence, this work suggests possible connections between the purinergic system and RA, proposing potential therapeutic targets against RA to be studied.

Coffee and multiple sclerosis (MS)

Multiple Sclerosis (MS) is a long-term autoimmune disorder affecting the central nervous system, marked by inflammation, demyelination, and neurodegeneration. While the exact cause of MS remains unknown, recent research indicates that environmental factors, particularly diet, may influence the disease's risk and progression. As a result, the potential neuroprotective effects of coffee, one of the most popular beverages worldwide, have garnered significant attention due to its rich content of bioactive compounds. This chapter explores the impact of coffee consumption on patients with Multiple Sclerosis, highlighting how coffee compounds like caffeine, polyphenols, and diterpenes can reduce inflammation and oxidative stress while enhancing neural function. It highlights caffeine's effect in regulating adenosine receptors, specifically A1R and A2AR, which play important roles in neuroinflammation and neuroprotection in MS. The dual role of microglial cells, which promote inflammation while also aiding neuroprotection, is also highlighted concerning caffeine's effects. Furthermore, the potential of A2AR as a therapeutic target in MS and the non-A2AR-dependent neuroprotective benefits of coffee. In this chapter we suggest that the consumption of coffee has no harmful effect on an MS patient and to a larger extent on public health, and informs future research directions and clinical practice, ultimately improving outcomes for individuals living with MS.

Hypoxia within the glioblastoma tumor microenvironment: a master saboteur of novel treatments

Glioblastoma (GBM) tumors are the most aggressive primary brain tumors in adults that, despite maximum treatment, carry a dismal prognosis. GBM tumors exhibit tissue hypoxia, which promotes tumor aggressiveness and maintenance of glioma stem cells and creates an overall immunosuppressive landscape. This article reviews how hypoxic conditions overlap with inflammatory responses, favoring the proliferation of immunosuppressive cells and inhibiting cytotoxic T cell development. Immunotherapies, including vaccines, immune checkpoint inhibitors, and CAR-T cell therapy, represent promising avenues for GBM treatment. However, challenges such as tumor heterogeneity, immunosuppressive TME, and BBB restrictiveness hinder their effectiveness. Strategies to address these challenges, including combination therapies and targeting hypoxia, are actively being explored to improve outcomes for GBM patients. Targeting hypoxia in combination with immunotherapy represents a potential strategy to enhance treatment efficacy.

Discovery of a potent, selective, and tumor-suppressing antibody antagonist of adenosine A2A receptor

New immune checkpoints are emerging in a bid to improve response rates to immunotherapeutic drugs. The adenosine A2A receptor (A2AR) has been proposed as a target for immunotherapeutic development due to its participation in immunosuppression of the tumor microenvironment. Blockade of A2AR could restore tumor immunity and, consequently, improve patient outcomes. Here, we describe the discovery of a potent, selective, and tumor-suppressing antibody antagonist of human A2AR (hA2AR) by phage display. We constructed and screened four single-chain variable fragment (scFv) libraries-two synthetic and two immunized-against hA2AR and antagonist-stabilized hA2AR. After biopanning and ELISA screening, scFv hits were reformatted to human IgG and triaged in a series of cellular binding and functional assays to identify a lead candidate. Lead candidate TB206-001 displayed nanomolar binding of hA2AR-overexpressing HEK293 cells; cross-reactivity with mouse and cynomolgus A2AR but not human A1, A2B, or A3 receptors; functional antagonism of hA2AR in hA2AR-overexpressing HEK293 cells and peripheral blood mononuclear cells (PBMCs); and tumor-suppressing activity in colon tumor-bearing HuCD34-NCG mice. Given its therapeutic properties, TB206-001 is a good candidate for incorporation into next-generation bispecific immunotherapeutics.

Subtle Structural Changes across the Boundary between A2AR/A2BR Dual Antagonism and A2BR Antagonism: A Novel Class of 2-Aminopyrimidine-Based Derivatives

Aberrantly elevated adenosine in the tumor microenvironment exerts its immunosuppressive functions through adenosine receptors A2AR and A2BR. Antagonism of A2AR and A2BR has the potential to suppress tumor growth. Herein, we report a systemic assessment of the effects of an indole modification at position 4, 5, 6, or 7 on both A2AR/A2BR activity and selectivity of novel 2-aminopyrimidine compounds. Substituting indole at the 4-/5-position produced potent A2AR/A2BR dual antagonism, whereas the 6-position of indole substitution gave highly selective A2BR antagonism. Molecular dynamics simulation showed that the 5-cyano compound 7ai had a lower binding free energy than the 6-cyano compound 7aj due to water-bridged hydrogen bond interactions with E169 or F168 in A2AR. Of note, dual A2AR/A2BR antagonism by compound 7ai can profoundly promote the activation and cytotoxic function of T cells. This work provided a strategy for obtaining novel dual A2AR/A2BR or A2BR antagonists by fine-tuning structural modification.

Adenosine Deaminase as a Potential Diagnostic and Prognostic Biomarker for Severe Fever with Thrombocytopenia Syndrome

BACKGROUND

Severe fever with thrombocytopenia syndrome (SFTS) is a serious infectious disease caused by the Dabie bandavirus, with a high mortality rate. Currently, there are no effective vaccines or specific treatments for SFTS. Early diagnosis and accurate severity assessment are crucial.

METHODS

This study included 171 cases of SFTS, COVID-19, and hepatitis B virus (HBV) patients and healthy controls. We compared the serum adenosine deaminase (ADA) activity across these groups. The diagnostic and prognostic efficiency of serum ADA for SFTS was evaluated by using receiver operating characteristic (ROC) curve analysis. We also examined the correlation between serum ADA in SFTS patients and clinical lab parameters as well as serum cytokines.

RESULTS

SFTS patients had significantly higher serum ADA activity than those of COVID-19, HBV patients, and healthy controls. Nonsurvivor SFTS patients had notably higher ADA than survivors. ROC analysis indicated ADA as an effective SFTS diagnostic and prognostic biomarker. ADA correlated with prognosis, viral load, APTT, PT, AST, ferritin, negatively with HDL-c and LDL-c, and positively with cytokines like IL-6, TNF-α, and IL-1β. Multiorgan failure patients showed significant ADA increase.

CONCLUSION

Elevated serum ADA activity in SFTS patients is linked with disease severity and prognosis, showing potential as a diagnostic and prognostic biomarker for SFTS.

Beyond FOXP3: a 20-year journey unravelling human regulatory T-cell heterogeneity

The initial idea of a distinct group of T-cells responsible for suppressing immune responses was first postulated half a century ago. However, it is only in the last three decades that we have identified what we now term regulatory T-cells (Tregs), and subsequently elucidated and crystallized our understanding of them. Human Tregs have emerged as essential to immune tolerance and the prevention of autoimmune diseases and are typically contemporaneously characterized by their CD3+CD4+CD25high CD127lowFOXP3+ phenotype. It is important to note that FOXP3+ Tregs exhibit substantial diversity in their origin, phenotypic characteristics, and function. Identifying reliable markers is crucial to the accurate identification, quantification, and assessment of Tregs in health and disease, as well as the enrichment and expansion of viable cells for adoptive cell therapy. In our comprehensive review, we address the contributions of various markers identified in the last two decades since the master transcriptional factor FOXP3 was identified in establishing and enriching purity, lineage stability, tissue homing and suppressive proficiency in CD4+ Tregs. Additionally, our review delves into recent breakthroughs in innovative Treg-based therapies, underscoring the significance of distinct markers in their therapeutic utilization. Understanding Treg subsets holds the key to effectively harnessing human Tregs for immunotherapeutic approaches.

Novel Adenosine Receptor Antagonists for Treating Cancer and Immune-Related Disorders

Provided herein are novel adenosine A2a receptor and adenosine A2b receptor inhibitors, pharmaceutical compositions, use of such compounds in treating cancer and immune-related disorders, and processes for preparing such compounds.