In Vitro, In Silico, and In Vivo Assessments of Pharmacokinetic Properties of ZM241385

A2AR antagonists triggered the AMPK/m-TOR autophagic pathway to reverse the calcium-dependent cell damage in 6-OHDA induced model of PD

Calcium dyshomeostasis, oxidative stress, autophagy and apoptosis are the pathogenesis of selective dopaminergic neuronal loss in Parkinson's disease (PD). Earlier, we reported that A2A R modulates IP3-dependent intracellular Ca2+ signalling via PKA. Moreover, A2A R antagonist has been reported to reduce oxidative stress and apoptosis in PD models, however intracellular Ca2+ ([Ca2+]i) dependent autophagy regulation in the 6-OHDA model of PD has not been explored. In the present study, we investigated the A2A R antagonists mediated neuroprotective effects in 6-OHDA-induced primary midbrain neuronal (PMN) cells and unilateral lesioned rat model of PD. 6-OHDA-induced oxidative stress (ROS and superoxide) and [Ca2+]i was measured using Fluo4AM, DCFDA and DHE dye respectively. Furthermore, autophagy was assessed by Western blot of p-m-TOR/mTOR, p-AMPK/AMPK, LC3I/II, Beclin and β-actin. Apoptosis was measured by Annexin V-APC-PI detection and Western blot of Bcl2, Bax, caspase3 and β-actin. Dopamine levels were measured by Dopamine ELISA kit and Western blot of tyrosine hydroxylase. Our results suggest that 6-OHDA-induced PMN cell death occurred due to the interruption of [Ca2+]i homeostasis, accompanied by activation of autophagy and apoptosis. A2A R antagonists prevented 6-OHDA-induced neuronal cell death by decreasing [Ca2+]i overload and oxidative stress. In addition, we found that A2A R antagonists upregulated mTOR phosphorylation and downregulated AMPK phosphorylation thereby reducing autophagy and apoptosis both in 6-OHDA induced PMN cells and 6-OHDA unilateral lesioned rat model. In conclusion, A2A R antagonists alleviated 6-OHDA toxicity by modulating [Ca2+]i signalling to inhibit autophagy mediated by the AMPK/mTOR pathway.

Improvement of the sepsis survival rate by adenosine 2a receptor antagonists depends on immune regulatory functions of regulatory T-cells

Adenosine shows a significant immunosuppressive effect in sepsis via binding to the adenosine 2a receptor (A2aR). Both genetic deletion and pharmacological inhibition of the A2aR may improve survival in sepsis. However, available research on this protective mechanism is quite limited. We used an A2aR antagonist (ZM241385) to treat a cecal ligation and puncture model of normal mice or regulatory T-cell (Treg)-depletion mice and found that the protective effect of ZM241385 is dependent on Tregs. Mechanically, A2aR inactivation was associated with decreased frequencies and reduced function of Foxp3+ Tregs, as evidenced by Foxp3 and CTLA-4 expression and classical effector T-cell proliferative assays, suggesting Treg modulation is a potential protective mechanism against sepsis. Simultaneously, the function and quantity of abdominal neutrophils were improved with ZM241385 treatment. To see if a link exists between them, Tregs and neutrophils were co-cultured, and it was found that ZM241385 blocked the inhibitory effect of Tregs on neutrophils. According to our research, Tregs play a key role in how A2aR antagonists improve sepsis prognosis and bacterial clearance.

Multifunctional Lipid Bilayer Nanocarriers for Cancer Immunotherapy in Heterogeneous Tumor Microenvironments, Combining Immunogenic Cell Death Stimuli with Immune Modulatory Drugs

In addition to the contribution of cancer cells, the solid tumor microenvironment (TME) has a critical role in determining tumor expansion, antitumor immunity, and the response to immunotherapy. Understanding the details of the complex interplay between cancer cells and components of the TME provides an unprecedented opportunity to explore combination therapy for intervening in the immune landscape to improve immunotherapy outcome. One approach is the introduction of multifunctional nanocarriers, capable of delivering drug combinations that provide immunogenic stimuli for improvement of tumor antigen presentation, contemporaneous with the delivery of coformulated drug or synthetic molecules that provide immune danger signals or interfere in immune-escape, immune-suppressive, and T-cell exclusion pathways. This forward-looking review will discuss the use of lipid-bilayer-encapsulated liposomes and mesoporous silica nanoparticles for combination immunotherapy of the heterogeneous immune landscapes in pancreatic ductal adenocarcinoma and triple-negative breast cancer. We describe how the combination of remote drug loading and lipid bilayer encapsulation is used for the synthesis of synergistic drug combinations that induce immunogenic cell death, interfere in the PD-1/PD-L1 axis, inhibit the indoleamine-pyrrole 2,3-dioxygenase (IDO-1) immune metabolic pathway, restore spatial access to activated T-cells to the cancer site, or reduce the impact of immunosuppressive stromal components. We show how an integration of current knowledge and future discovery can be used for a rational approach to nanoenabled cancer immunotherapy.

A2A Adenosine Receptor Antagonists and their Potential in Neurological Disorders

Endogenous nucleoside adenosine modulates a number of physiological effects through interaction with P1 purinergic receptors. All of them are G protein coupled receptors and, to date, four subtypes have been characterized and named A1, A2A, A2B, and A3. In recent years adenosine receptors, particularly the A2A subtype, have become attractive targets for the treatment of several neurodegenerative disorders, known to involve neuroinflammation, like Parkinson's and Alzheimer's diseases, multiple sclerosis and neuropsychiatric conditions. In fact, it has been demonstrated that inhibition of A2A adenosine receptors exerts neuroprotective effects counteracting neuroinflammatory processes and astroglial and microglial activation. The A2A adenosine receptor antagonist istradefylline, developed by Kyowa Hakko Kirin Inc., was approved in Japan as adjunctive therapy for the treatment of Parkinson's disease and very recently it was approved also by the US Food and Drug Administration. These findings pave the way for new therapeutic opportunities, so, in this review, a summary of the most relevant and promising A2A adenosine receptor antagonists will be presented along with their preclinical and clinical studies in neuroinflammation related diseases.

Structure-Based Design of Dual-Acting Compounds Targeting Adenosine A2A Receptor and Histone Deacetylase as Novel Tumor Immunotherapeutic Agents

Adenosine is an immunosuppressive factor in the tumor microenvironment mainly through activation of the A_2A adenosine receptor (A_2AR), which is a mechanism hijacked by tumors to escape immune surveillance. Small-molecule A_2AR antagonists are being evaluated in clinical trials as immunotherapeutic agents, but their efficacy is limited as standalone therapies. To enhance the antitumor effects of A_2AR antagonists, dual-acting compounds incorporating A_2AR antagonism and histone deacetylase (HDAC) inhibitory actions were designed and synthesized, based on co-crystal structures of A_2AR. Compound 24e (IHCH-3064) exhibited potent binding to A_2AR (K_i = 2.2 nM) and selective inhibition of HDAC1 (IC₅₀ = 80.2 nM), with good antiproliferative activity against tumor cell lines in vitro. Intraperitoneal administration of 24e (60 mg/kg, bid) inhibited mouse MC38 tumor growth with a tumor growth inhibition rate of 95.3%. These results showed that dual-acting compounds targeting A_2AR and HDAC are potentially immunotherapeutic agents that are worth further exploring.

Purines and Pyrimidines: Metabolism, Function and Potential as Therapeutic Options in Neurodegenerative Diseases

Various neurodegenerative disorders have various molecular origins but some common molecular mechanisms. In the current scenario, there are very few treatment regimens present for advanced neurodegenerative diseases. In this context, there is an urgent need for alternate options in the form of natural compounds with an ameliorating effect on patients. There have been individual scattered experiments trying to identify potential values of various intracellular metabolites. Purines and Pyrimidines, which are vital molecules governing various aspects of cellular biochemical reactions, have been long sought as crucial candidates for the same, but there are still many questions that go unanswered. Some critical functions of these molecules associated with neuromodulation activities have been identified. They are also known to play a role in foetal neurodevelopment, but there is a lacuna in understanding their mechanisms. In this review, we have tried to assemble and identify the importance of purines and pyrimidines, connecting them with the prevalence of neurodegenerative diseases. The leading cause of this class of diseases is protein misfolding and the formation of amyloids. A direct correlation between loss of balance in cellular homeostasis and amyloidosis is yet an unexplored area. This review aims at bringing the current literature available under one umbrella serving as a foundation for further extensive research in this field of drug development in neurodegenerative diseases.

Suppression of adenosine A2a receptors alleviates bladder overactivity and hyperalgesia in cyclophosphamide-induced cystitis by inhibiting TRPV1

Interstitial cystitis/bladder pain syndrome (IC/BPS) is a type of chronic bladder inflammation characterized by increased voiding frequency, urgency and pelvic pain. The sensitization of bladder afferents is widely regarded as one of the pathophysiological changes in the development of IC/BPS. There is evidence that adenosine A_2a receptors are involved in regulating the sensitization of sensory afferents. However, the effect of adenosine A_2a receptors on cystitis remains unknown. In the present study, a rat model of chronic cystitis was established by intraperitoneal injection with cyclophosphamide (CYP). Cystometry and behavioral tests were performed to investigate bladder micturition function and nociceptive pain. The rats with chronic cystitis showed symptoms of bladder overactivity, characterized by an increase in bladder voiding frequency and voiding pressure. CYP treatment significantly increased the expression of the A_2a receptor in bladder afferent fibers and dorsal root ganglion (DRG) neurons. The A_2a receptor antagonist ZM241385 prevented bladder overactivity and hyperalgesia elicited by CYP-induced cystitis. In addition, the A_2a receptor and TRPV1 were coexpressed on DRG neurons. The TRPV1 antagonist capsazepine blocked bladder overactivity induced by the A_2a receptor agonist CGS21680. In contrast, ZM241385 significantly inhibited the capsaicin-induced increase in intracellular calcium concentration in DRG neurons. These results suggest that suppression of adenosine A_2a receptors in bladder afferents alleviates bladder overactivity and hyperalgesia elicited by CYP-induced cystitis in rats by inhibiting TRPV1, indicating that the adenosine A_2a receptor in bladder afferents is a potential therapeutic target for the treatment of IC/BPS.