Synergistic effect of tumor chemo-immunotherapy induced by leukocyte-hitchhiking thermal-sensitive micelles

Some specific chemotherapeutic drugs are able to enhance tumor immunogenicity and facilitate antitumor immunity by inducing immunogenic cell death (ICD). However, tumor immunosuppression induced by the adenosine pathway hampers this effect. In this study, E-selectin-modified thermal-sensitive micelles are designed to co-deliver a chemotherapeutic drug (doxorubicin, DOX) and an A2A adenosine receptor antagonist (SCH 58261), which simultaneously exhibit chemo-immunotherapeutic effects when applied with microwave irradiation. After intravenous injection, the fabricated micelles effectively adhere to the surface of leukocytes in peripheral blood mediated by E-selectin, and thereby hitchhiking with leukocytes to achieve a higher accumulation at the tumor site. Further, local microwave irradiation is applied to induce hyperthermia and accelerates the release rate of drugs from micelles. Rapidly released DOX induces tumor ICD and elicits tumor-specific immunity, while SCH 58261 alleviates immunosuppression caused by the adenosine pathway, further enhancing DOX-induced antitumor immunity. In conclusion, this study presents a strategy to increase the tumor accumulation of drugs by hitchhiking with leukocytes, and the synergistic strategy of chemo-immunotherapy not only effectively arrested primary tumor growth, but also exhibited superior effects in terms of antimetastasis, antirecurrence and antirechallenge.

Synergistic effect of tumor chemo-immunotherapy induced by leukocyte-hitchhiking thermal-sensitive micelles

Some specific chemotherapeutic drugs are able to enhance tumor immunogenicity and facilitate antitumor immunity by inducing immunogenic cell death (ICD). However, tumor immunosuppression induced by the adenosine pathway hampers this effect. In this study, E-selectin-modified thermal-sensitive micelles were designed to co-deliver a chemotherapeutic drug (doxorubicin, DOX) and an A2A adenosine receptor antagonist (SCH 58261), which simultaneously exhibited chemo-immunotherapeutic effects when applied with microwave irradiation. After intravenous injection, the fabricated micelles, ES-DSM, effectively adhered to the surface of leukocytes in peripheral blood mediated by E-selectin, and thereby hitchhiking with leukocytes to achieve a higher accumulation at the tumor site. Further, local microwave irradiation was applied to induce hyperthermia and accelerated the release rate of drugs from micelles. Rapidly released DOX induced tumor ICD and elicited tumor-specific immunity, while SCH 58261 alleviated immunosuppression caused by the adenosine pathway, further enhancing DOX-induced antitumor immunity. In conclusion, this study presents a strategy to increase the tumor accumulation of drugs by hitchhiking with leukocytes, and the synergistic strategy of chemo-immunotherapy not only effectively arrested primary tumor growth, but also exhibited superior effects in terms of antimetastasis, antirecurrence and antirechallenge.

Enhancement of Ketone Supplements-Evoked Effect on Absence Epileptic Activity by Co-Administration of Uridine in Wistar Albino Glaxo Rijswijk Rats

Both uridine and exogenous ketone supplements decreased the number of spike-wave discharges (SWDs) in a rat model of human absence epilepsy Wistar Albino Glaxo/Rijswijk (WAG/Rij) rats. It has been suggested that alleviating influence of both uridine and ketone supplements on absence epileptic activity may be modulated by A1 type adenosine receptors (A1Rs). The first aim was to determine whether intraperitoneal (i.p.) administration of a specific A1R antagonist 1,3-dipropyl-8-cyclopentylxanthine (DPCPX; 0.2 mg/kg) and a selective adenosine A2A receptor antagonist (7-(2-phenylethyl)-5-amino-2-(2-furyl)-pyrazolo-[4,3-e]-1,2,4-triazolo [1,5-c]pyrimidine) (SCH 58261; 0.5 mg/kg) have a modulatory influence on i.p. 1000 mg/kg uridine-evoked effects on SWD number in WAG/Rij rats. The second aim was to assess efficacy of a sub-effective dose of uridine (i.p. 250 mg/kg) combined with beta-hydroxybutyrate salt + medium chain triglyceride (KSMCT; 2.5 g/kg, gavage) on absence epilepsy. DPCPX completely abolished the i.p. 1000 mg/kg uridine-evoked alleviating effect on SWD number whereas SCH 58261 was ineffective, confirming the A1R mechanism. Moreover, the sub-effective dose of uridine markedly enhanced the effect of KSMCT (2.5 g/kg, gavage) on absence epileptic activity. These results demonstrate the anti-epilepsy benefits of co-administrating uridine and exogenous ketone supplements as a means to treat absence epilepsy.

Assessment of Pharmacokinetics and Metabolism Profiles of SCH 58261 in Rats Using Liquid Chromatography–Mass Spectrometric Method

5-Amino-7-(2-phenylethyl)-2-(2-furyl)-pyrazolo(4,3-e)-1,2,4-triazolo(1,5-c) pyrimidine (SCH 58261) is one of the new chemical entities that has been developed as an adenosine A2A receptor antagonist. Although SCH 58261 has been reported to be beneficial, there is little information about SCH 58261 from a drug metabolism or pharmacokinetics perspective. This study describes the metabolism and pharmacokinetic properties of SCH 58261 in order to understand its behaviors in vivo. Rats were used as the in vivo model species. First, an LC–MS/MS method was developed for the determination of SCH 58261 in rat plasma. A GastroPlus™ simulation, in vitro microsomal metabolic stability, and bile duct-cannulated studies were also performed to understand its pharmacokinetic profile. The parameter sensitivity analysis of GastroPlus™ was used to examine the factors that influence exposure when the drug is orally administered. The factors are as follows: permeability, systemic clearance, renal clearance, and liver first-pass effect. In vitro microsomal metabolic stability indicates how much the drug is metabolized. The extrapolated hepatic clearance value of SCH 58261 was 39.97 mL/min/kg, indicating that the drug is greatly affected by hepatic metabolism. In vitro microsomal metabolite identification studies revealed that metabolites produce oxidized and ketone-formed metabolites via metabolic enzymes in the liver. The bile duct-cannulated rat study, after oral administration of SCH 58261, showed that a significant amount of the drug was excreted in feces. These results imply that the drug is not absorbed well in the body after oral administration. Taken together, SCH 58261 showed quite a low bioavailability when administered orally and this was likely due to significantly limited absorption, as well as high metabolism in vivo.

Neuronal adenosine A2A receptors signal ergogenic effects of caffeine

Ergogenic aid is a substance or method used for enhancing exercise and sports performance. Caffeine is the most used ergogenic aid for athletes, but the mechanisms are still unknown. Forty-two adult female (19±0.6 g) and 40 male mice (24±0.4 g) from a global and forebrain A2AR knockout and colony (FMUC, University of Coimbra) underwent an open field and ergospirometry exercise test. Caffeine (15 mg/kg, i.p.) and SCH 58261 (1 mg/kg, i.p.) were administered 15 minutes before the animals ran to exhaustion. We also evaluate the estrous cycle and infrared temperature (rest and recovery). Caffeine was psychostimulant in wild type females and males, but we observed this expected effect of SCH-58261 only in males. Caffeine and SCH-58261 were also ergogenic for wild type animals, that is, they increased running power and maximal O2 consumption (O2max). The psychostimulant and ergogenic effects of caffeine and SCH-58261 disappeared in A2AR knockout females (global) and males (forebrain). The estrous cycle did not influence any evaluated parameters, as well as exercise-induced hyperthermia was similar between savages and knockouts. Our results suggest that the neuronal A2AR receptors signal the ergogenic effects of caffeine in female and male mice.

Inhibition of adenosine A1 receptors abolished the nutritional ketosis-evoked delay in the onset of isoflurane-induced anesthesia in Wistar Albino Glaxo Rijswijk rats

Background: It has been demonstrated that administration of exogenous ketone supplement ketone salt (KS) and ketone ester (KE) increased blood ketone level and delayed the onset of isoflurane-induced anesthesia in different rodent models, such as Wistar Albino Glaxo Rijswijk (WAG/Rij) rats. The modulatory effect of adenosinergic system may have a role in the ketone supplementation-evoked effects on isoflurane-generated anesthesia. Thus, we investigated whether adenosine receptor antagonists can modulate the effect of exogenous ketone supplements on the onset of akinesia induced by isoflurane. Methods: To investigate the effect of exogenous ketone supplements on anesthetic induction we used ketone supplement KE, KS, KEKS (1:1 mix of KE and KS), KSMCT and KEMCT (1:1 mix of KS and KE with medium chain triglyceride/MCT oil, respectively) in WAG/Rij rats. Animals were fed with standard diet (SD), which was supplemented by oral gavage of different ketone supplements (2.5 g/kg/day) for 1 week. After 7 days, isoflurane (3%) was administered for 5 min and the time until onset of isoflurane-induced anesthesia (time until immobility; light phase of anesthesia: loss of consciousness without movement) was measured. Changes in levels of blood β-hydroxybutyrate (βHB), blood glucose and body weight of animals were also recorded. To investigate the putative effects of adenosine receptors on ketone supplements-evoked influence on isoflurane-induced anesthesia we used a specific adenosine A1 receptor antagonist DPCPX (intraperitoneally/i.p. 0.2 mg/kg) and a selective adenosine A2A receptor antagonist SCH 58261 (i.p. 0.5 mg/kg) alone as well as in combination with KEKS. Results: Significant increases were demonstrated in both blood βHB levels and the number of seconds required before isoflurane-induced anesthesia (immobility) after the final treatment by all exogenous ketone supplements. Moreover, this effect of exogenous ketone supplements positively correlated with blood βHB levels. It was also demonstrated that DPCPX completely abolished the effect of KEKS on isoflurane-induced anesthesia (time until immobility), but not SCH 58261. Conclusions: These findings strengthen our previous suggestion that exogenous ketone supplements may modulate the isoflurane-induced onset of anesthesia (immobility), likely through A1Rs.

Inhibition of adenosine A1 receptors abolished the nutritional ketosis-evoked delay in the onset of isoflurane-induced anesthesia in Wistar Albino Glaxo Rijswijk rats

Background It has been demonstrated that administration of exogenous ketone supplement ketone salt (KS) and ketone ester (KE) increased blood ketone level and delayed the onset of isoflurane-induced anesthesia (immobility) in different rodent models, such as Wistar Albino Glaxo Rijswijk (WAG/Rij) rats. The modulatory effect of adenosinergic system may have a role in the ketone supplementation-evoked effects on isoflurane-generated anesthesia. Thus, we investigated whether adenosine receptor antagonists can modulate the effect of exogenous ketone supplements on the onset of akinesia induced by isoflurane.Methods To investigate the effect of exogenous ketone supplements on anesthetic induction we used ketone supplement KE, KS, KEKS (1:1 mix of KE and KS), KSMCT and KEMCT (1:1 mix of KS and KE with medium chain triglyceride/MCT oil, respectively) in WAG/Rij rats. Animals were fed with standard diet, which was supplemented by oral gavage of different ketone supplements (2.5 g/kg/day) for 1 week. After 7 days, isoflurane (3%) was administered for 5 min and the time until onset of isoflurane-induced anesthesia (immobility) was measured. Changes in levels of blood β-hydroxybutyrate (βHB), blood glucose and body weight of animals were also recorded. To investigate the putative effects of adenosine receptors on ketone supplements-evoked influence on isoflurane-induced anesthesia we used a specific adenosine A1 receptor antagonist DPCPX (intraperitoneally/i.p. 0.2 mg/kg) and a selective adenosine A2A receptor antagonist SCH 58261 (i.p. 0.5 mg/kg) in combination with KEKS.Results Significant increases were demonstrated in both blood βHB levels and the number of seconds required before isoflurane-induced anesthesia (immobility) after the final treatment by all exogenous ketone supplements. Moreover, this effect of exogenous ketone supplements positively correlated with blood βHB levels. It was also demonstrated that DPCPX completely abolished the effect of KEKS on isoflurane-induced anesthesia (immobility), but not SCH 58261.Conclusions These findings strengthen our previous suggestion that exogenous ketone supplements-evoked increase in ketone levels (ketosis) might affect surgical anesthetic needs. Moreover, our results demonstrate that adenosinergic system (likely through A1Rs) may modulate the influence of exogenous ketone supplements-evoked ketosis on isoflurane-generated anesthesia.

Anticancer Effects of Cordyceps Militaris Extract in Human Ovarian Cancer Cells via ADORA2B (P05-012-19)

Objectives The study was aimed to determine anticancer effects of Cordyceps militaris extract (CME) and its major bioactive compound, cordycepin, in human ovarian cancer cells, and to identify their putative molecular mechanism mediated by adenosine receptors (ADORAs). Methods CME was prepared in 50% ethanol solution. LC-MS was used for quantification and Q-TOF MS for qualifying bioactive compounds in CME. MTT assay was performed for cell viability in A2780, SKOV-3, TOV112D, and OVCAR-3 human ovarian cancer cell lines. cAMP response element (CRE)-luciferase reporter gene assays were used to determine whether antitumorigenic effect of CME/cordycepin is based on adenosine derivatives. Additionally, the involvement of ADORA signaling pathway was measured using with ADORA2A antagonist SCH 58261 and ADORA2B antagonist PSB 603. Results Cordycepin concentrations of CME was 21.8%. CME was effective to reduce cell viability in A2780 and OVCAR-3 with IC50 115.2 μg/ml and 155.94 μg/ml respectively, while SKOV-3 and TOV112D were relatively resistant to CME. cAMP production was significantly increased by treatment with cordycepin and, lesser extent, with CME. Among the four types of ADORAs, ADORA2A and 2B showed relatively higher expression levels in ovarian cancer cells. The cAMP production by CME was ameliorated by PSB 603, not SCH 58261, treatment. Conclusions CME and cordycepin have anticancer effects in human ovarian cancer cells via ADORA2B-cAMP pathway. Funding Sources NRF of Korea (2017R1D1A1B03034936 & 22A20130012143) and Health Fellowship Foundation.

Adenosine Regulation of cAMP through Phosphodiesterases

Introduction: Adenosine, an autacoid and metabolite of ATP, has been known to have anti-platelet properties. Of the 4 adenosine receptors (ARs), only A2A AR have been implicated in adenosines anti-platelet properties in human. A2A AR is a G-Protein Coupled Receptors associated with a stimulatory G-Protein (Gs) that can activate adenylyl cyclase (AC) and increase intracellular cAMP. An elevation of cAMP has been shown to inhibit platelet aggregation to natural stimuli. Regulation of intracellular cAMP is balanced between synthesis by adenylate cyclase and degradation by phosphdiesterases (PDE). There are 3 PDE subtypes found in platelets: PDE2, PDE3, and PDE5. However, it is not know which subtype(s) is (are) responsible for regulating cAMP level in human platelets after adenosine stimulation. Materials and Methods: Platelet-rich plasma (PRP) was isolated from whole blood of human volunteers, and centrifuged at 200g for 10min. Light transmission aggregometry was performed after stimulation of platelets with 100uM ADP, with or without NECA (non-specific AR agonist), DPCPX (A1 AR antagonist), and Sch 58261 (A2A AR antagonist). PRP treated with NECA, DPCPX, Sch 58261, and PDE inhibitors (EHNA, E in figures, for PDE2, Trequinsin, T in figures, for PDE3, and 4-{[3'4'-(methylenedioxy) benzyl]amino}-6-methoxyqunazolin, 4 in figures, for PDE 5). Cyclic AMP was measured in platelets after treatment by liquid chromatography/ Tandem Mass Spectroscopy (Quantiva, ThrermoFisher) after treated with these drugs. Results: ADP-induced platelet aggregation was inhibited in a dose dependent manner by the non-specific adenosine agonist, NECA (Figure 1) and the effect was blocked by A2A specific antagonist Sch 58261, not by the A1 AR antagonist, DPCPX (Figure 2). NECA inhibition of platelet aggregation was likely due to an elevation of intracellular cAMP (1 uM, 5min incubation, Figure 3). Inhibition of PDE3 alone, significantly increased intracellular cAMP, suggesting that basal PDE3 activity is present. PDE 3 inhibition combined with NECA elevated cAMP even higher than PDE inhibition or NECA alone (Figure 3), suggesting that NECA (A2A stimulation) effects PDE activity. Inhibition of PDE2 or 5 had no effect on basal or NECA stimulated cAMP (Figure 3). Inhibition of all 3 PDE (2,3,5) combined with NECA elevated cAMP to levels higher then NECA+ PDE3 inhibition, again suggesting that NECA maybe effecting the activity of the PDEs (Figure 3). The potentiation of cAMP by PDE3 inhibition + NECA was block by A2A, but not A1 antagonist (Figure 4) suggesting that the nonspecific adenosine agonist is elevating cAMP through A2A. Conclusion: 1. In human platelets, NECA stimulates cAMP through A2A receptors and this elevation is likely due to an elevation in adenylate cyclase via Gs coupled to A2A. PDE3 is basally active and likely regulated by adenosine receptors. Disclosures No relevant conflicts of interest to declare.