Methylation-regulated tumor suppressor gene PDE7B promotes HCC invasion and metastasis through the PI3K/AKT signaling pathway.

BACKGROUND: Hepatocellular carcinoma (HCC) has a high mortality rate, and the mechanisms underlying tumor development and progression remain unclear. However, inactivated tumor suppressor genes might play key roles. DNA methylation is a critical regulatory mechanism for inactivating tumor suppressor genes in HCC. Therefore, this study investigated methylation-related tumor suppressors in HCC to identify potential biomarkers and therapeutic targets. METHODS: We assessed genome-wide DNA methylation in HCC using whole genome bisulfite sequencing (WGBS) and RNA sequencing, respectively, and identified the differential expression of methylation-related genes, and finally screened phosphodiesterase 7B (PDE7B) for the study. The correlation between PDE7B expression and clinical features was then assessed. We then analyzed the changes of PDE7B expression in HCC cells before and after DNA methyltransferase inhibitor treatment by MassArray nucleic acid mass spectrometry. Furthermore, HCC cell lines overexpressing PDE7B were constructed to investigate its effect on HCC cell function. Finally, GO and KEGG were applied for the enrichment analysis of PDE7B-related pathways, and their effects on the expression of pathway proteins and EMT-related factors in HCC cells were preliminarily explored. RESULTS: HCC exhibited a genome-wide hypomethylation pattern. We screened 713 hypomethylated and 362 hypermethylated mCG regions in HCC and adjacent normal tissues. GO analysis showed that the main molecular functions of hypermethylation and hypomethylation were "DNA-binding transcriptional activator activity" and "structural component of ribosomes", respectively, whereas KEGG analysis showed that they were enriched in "bile secretion" and "Ras-associated protein-1 (Rap1) signaling pathway", respectively. PDE7B expression was significantly down-regulated in HCC tissues, and this low expression was negatively correlated with recurrence and prognosis of HCC. In addition, DNA methylation regulates PDE7B expression in HCC. On the contrary, overexpression of PDE7B inhibited tumor proliferation and metastasis in vitro. In addition, PDE7B-related genes were mainly enriched in the PI3K/ATK signaling pathway, and PDE7B overexpression inhibited the progression of PI3K/ATK signaling pathway-related proteins and EMT. CONCLUSION: PDE7B expression in HCC may be regulated by promoter methylation. PDE7B can regulate the EMT process in HCC cells through the PI3K/AKT pathway, which in turn affects HCC metastasis and invasion.

Role and mechanism of Circ-PDE7B in the formation of keloid.

The excessive proliferation of keloid fibroblasts is one of the important reasons leading to the formation of keloids. Circular RNA (circRNA) is an important regulator that regulates the biological functions of cells. However, the role and mechanism of circ-PDE7B in keloid formation have not been studied yet. QRT-PCR was used to detect the circ-PDE7B, miR-331-3p and cyclin-dependent kinase 6 (CDK6) expression. The biological functions of keloid fibroblasts were determined by MTT assay, flow cytometry, transwell assay and wound healing assay. Western blot analysis was used to measure the protein levels of extracellular matrix (ECM) markers and CDK6. The interaction between miR-331-3p and circ-PDE7B or CDK6 was confirmed by dual-luciferase reporter assay and RIP assay. Circ-PDE7B was found to be upregulated in keloid tissues and fibroblasts. Downregulation of circ-PDE7B could suppress the proliferation, invasion, migration, ECM accumulation and accelerate the apoptosis of keloid fibroblasts. Circ-PDE7B could serve as a sponge of miR-331-3p, and the regulation of silenced circ-PDE7B on the biological functions of keloid fibroblasts could be abolished by miR-331-3p inhibitor. Additionally, CDK6 was a target of miR-331-3p, and its overexpression could reverse the negative regulation of miR-331-3p on the biological functions of keloid fibroblasts. Circ-PDE7B sponged miR-331-3p to positively regulate CDK6 expression. Taken together, circ-PDE7B promoted the proliferation, invasion, migration and ECM accumulation of keloid fibroblasts by regulating the miR-331-3p/CDK6 axis, suggesting that circ-PDE7B might be a potential target for keloid treatment.

Unleashing Spinal Cord Repair: The Role of cAMP-Specific PDE Inhibition in Attenuating Neuroinflammation and Boosting Regeneration after Traumatic Spinal Cord Injury.

Traumatic spinal cord injury (SCI) is characterized by severe neuroinflammation and hampered neuroregeneration, which often leads to permanent neurological deficits. Current therapies include decompression surgery, rehabilitation, and in some instances, the use of corticosteroids. However, the golden standard of corticosteroids still achieves minimal improvements in functional outcomes. Therefore, new strategies tackling the initial inflammatory reactions and stimulating endogenous repair in later stages are crucial to achieving functional repair in SCI patients. Cyclic adenosine monophosphate (cAMP) is an important second messenger in the central nervous system (CNS) that modulates these processes. A sustained drop in cAMP levels is observed during SCI, and elevating cAMP is associated with improved functional outcomes in experimental models. cAMP is regulated in a spatiotemporal manner by its hydrolyzing enzyme phosphodiesterase (PDE). Growing evidence suggests that inhibition of cAMP-specific PDEs (PDE4, PDE7, and PDE8) is an important strategy to orchestrate neuroinflammation and regeneration in the CNS. Therefore, this review focuses on the current evidence related to the immunomodulatory and neuroregenerative role of cAMP-specific PDE inhibition in the SCI pathophysiology.

Phosphodiesterase 7 as a therapeutic target - Where are we now?

Cyclic nucleotide phosphodiesterases (PDEs) are a superfamily of enzymes that hydrolyse the intracellular second messengers cAMP and cGMP to their inactive forms 5'AMP and 5'GMP. Some members of the PDE family display specificity towards a single cyclic nucleotide messenger, and PDE4, PDE7, and PDE8 specifically hydrolyse cAMP. While the role of PDE4 and its use as a therapeutic target have been well studied, less is known about PDE7 and PDE8. This review aims to collate the present knowledge on human PDE7 and outline its potential use as a therapeutic target. Human PDE7 exists as two isoforms PDE7A and PDE7B that display different expression patterns but are predominantly found in the central nervous system, immune cells, and lymphoid tissue. As a result, PDE7 is thought to play a role in T cell activation and proliferation, inflammation, and regulate several physiological processes in the central nervous system, such as neurogenesis, synaptogenesis, and long-term memory formation. Increased expression and activity of PDE7 has been detected in several disease states, including neurodegenerative diseases such as Parkinson's, Alzheimer's and Huntington's disease, autoimmune diseases such as multiple sclerosis and COPD, and several types of cancer. Early studies have shown that administration of PDE7 inhibitors may ameliorate the clinical state of these diseases. Targeting PDE7 may therefore provide a novel therapeutic strategy for targeting a broad range of disease and possibly provide a complementary alternative to inhibitors of other cAMP-selective PDEs, such as PDE4, which are severely limited by their side-effects.

Advances in the development of phosphodiesterase 7 inhibitors.

Phosphodiesterase 7 (PDE7) specifically hydrolyzes cyclic adenosine monophosphate (cAMP), a second messenger that plays essential roles in cell signaling and physiological processes. Many PDE7 inhibitors used to investigate the role of PDE7 have displayed efficacy in the treatment of a wide range of diseases, such as asthma and central nervous system (CNS) disorders. Although PDE7 inhibitors are developed more slowly than PDE4 inhibitors, there is increasing recognition of PDE7 inhibitors as potential therapeutics for no nausea and vomiting secondary. Herein, we summarized the advances in PDE7 inhibitors over the past decade, focusing on their crystal structures, key pharmacophores, subfamily selectivity, and therapeutic potential. Hopefully, this summary will lead to a better understanding of PDE7 inhibitors and provide strategies for developing novel therapies targeting PDE7.

Neuronal lack of PDE7a disrupted working memory, spatial learning, and memory but facilitated cued fear memory in mice.

BACKGROUND: PDEs regulate cAMP levels which is critical for PKA activity-dependent activation of CREB-mediated transcription in learning and memory. Inhibitors of PDEs like PDE4 and Pde7 improve learning and memory in rodents. However, the role of PDE7 in cognition or learning and memory has not been reported yet. METHODS: Therefore, we aimed to explore the cognitive effects of a PDE7 subtype, PDE7a, using combined pharmacological and genetic approaches. RESULTS: PDE7a-nko mice showed deficient working memory, impaired novel object recognition, deficient spatial learning & memory, and contextual fear memory, contrary to enhanced cued fear memory, highlighting the potential opposite role of PDE7a in the hippocampal neurons. Further, pharmacological inhibition of PDE7 by AGF2.20 selectively strengthens cued fear memory in C57BL/6 J mice, decreasing its extinction but did not affect cognitive processes assessed in other behavioral tests. The further biochemical analysis detected deficient cAMP in neural cell culture with genetic excision of the PDE7a gene, as well as in the hippocampus of PDE7a-nko mice in vivo. Importantly, we found overexpression of PKA-R and the reduced level of pPKA-C in the hippocampus of PDE7a-nko mice, suggesting a novel mechanism of the cAMP regulation by PDE7a. Consequently, the decreased phosphorylation of CREB, CAMKII, eif2a, ERK, and AMPK, and reduced total level of NR2A have been found in the brain of PDE7a-nko animals. Notably, genetic excision of PDE7a in neurons was not able to change the expression of NR2B, BDNF, synapsin1, synaptophysin, or snap25. CONCLUSION: Altogether, our current findings demonstrated, for the first time, the role of PDE7a in cognitive processes. Future studies will untangle PDE7a-dependent neurobiological and molecular-cellular mechanisms related to cAMP-associated disorders.

The Dual PDE7-GSK3ß Inhibitor, VP3.15, as Neuroprotective Disease-Modifying Treatment in a Model of Primary Progressive Multiple Sclerosis.

Multiple sclerosis (MS) is a chronic, inflammatory, autoimmune and degenerative disease with axonal damage and demyelination as its main features. Its dual neurological and autoimmune nature makes it a disease that is difficult to treat. Treatments that simultaneously stop the immune response while protecting and repairing the nervous system are urgent. That is of utmost importance for the primary progressive multiple sclerosis (PPMS), a rare and severe variant of MS, characterized by worsening neurological function from the onset of symptoms. In this sense, inhibitors of glycogen synthase kinase 3ß (GSK3ß) and phosphodiesterase 7 (PDE7) have recently shown great therapeutic potential for the treatment of demyelinating diseases. Here we investigated a dual inhibitor of these two targets, the small molecule VP3.15, in a preclinical model, which resembles primary-progressive MS (PPMS), the Theiler's mouse encephalomyelitis virus-induced demyelinated disease (TMEV-IDD). In our study, VP3.15 ameliorates the disease course improving motor deficits of infected mice. Chronic treatment with VP3.15 also showed significant efficacy in the immunomodulation process, as well as in the proliferation and differentiation of oligodendroglial precursors, improving the preservation of myelin and axonal integrity. Therefore, our results support a treatment with the safe VP3.15 as an integrative therapeutic strategy for the treatment of PPMS.

Pharmacological modulation of phosphodiesterase-7 as a novel strategy for neurodegenerative disorders.

Neurodegenerative illness develops as a result of genetic defects that cause changes at numerous levels, including genomic products and biological processes. It entails the degradation of cyclic nucleotides, cyclic adenosine monophosphate (cAMP), and cyclic guanosine monophosphate (cGMP). PDE7 modulates intracellular cAMP signalling, which is involved in numerous essential physiological and pathological processes. For the therapy of neurodegenerative illnesses, the normalization of cyclic nucleotide signalling through PDE inhibition remains intriguing. In this article, we shall examine the role of PDEs in neurodegenerative diseases. Alzheimer's disease, Multiple sclerosis, Huntington's disease, Parkinson's disease, Stroke, and Epilepsy are related to alterations in PDE7 expression in the brain. Earlier, animal models of neurological illnesses including Alzheimer's disease, Parkinson's disease, and multiple sclerosis have had significant results to PDE7 inhibitors, i.e., VP3.15; VP1.14. In addition, modulation of CAMP/CREB/GSK/PKA signalling pathways involving PDE7 in neurodegenerative diseases has been addressed. To understand the etiology, treatment options of these disorders mediated by PDE7 and its subtypes can be the focus of future research.

Automated radiosynthesis of [11 C]MTP38-a phosphodiesterase 7 imaging tracer-using [11 C]hydrogen cyanide for clinical applications.

We have developed 8-amino-3-(2S,5R-dimethyl-1-piperidyl)-[1,2,4]triazolo[4,3-a]pyrazine-5-[11 C]carbonitrile ([11 C]MTP38) as a positron emission tomography (PET) tracer for the imaging of phosphodiesterase 7. For the fully automated production of [11 C]MTP38 routinely and efficiently for clinical applications, we determined the radiosynthesis procedure of [11 C]MTP38 using [11 C]hydrogen cyanide ([11 C]HCN) as a PET radiopharmaceutical. Radiosynthesis of [11 C]MTP38 was performed using an automated 11 C-labeling synthesizer developed in-house within 40 min after the end of irradiation. [11 C]MTP38 was obtained with a relatively high radiochemical yield (33 ± 5.5% based on [11 C]CO2 at the end of irradiation, decay-corrected, n = 15), radiochemical purity (>97%, n = 15), and molar activity (47 ± 12 GBq/µmol at the end of synthesis, n = 15). All the results of the quality control (QC) testing for the [11 C]MTP38 injection complied with our in-house QC and quality assurance specifications. We successfully automated the radiosynthesis of [11 C]MTP38 for clinical applications using an 11 C-labeling synthesizer and sterile isolator. Taken together, this protocol provides a new radiopharmaceutical [11 C]MTP38 suitable for clinical applications.

The effects of BRL-50481 on ovalbumin-induced asthmatic lung inflammation exacerbated by co-exposure to Asian sand dust in the murine model.

Asian sand dust (ASD), which mainly originates in China and Mongolia in the spring and blows into Korea, can exacerbate respiratory and immunological diseases. This study aims to observe effects of co-exposure to ASD on ovalbumin (OVA)-induced asthmatic lung inflammation and of treatment with a phosphodiesterase 7 (PDE7) inhibitor in a mouse model. The challenge with OVA increased airway hyperresponsiveness (AHR) and inflammatory cell infiltration into the lung tissue. Interleukin (IL)-13, tumor necrosis factor-alpha, monocyte-protein-1, mucin, and antigen-specific IgE and IgG1 production increased in mouse serum. The co-exposure of ASD significantly exacerbated these effects in this asthma model. Notably, the administration of a PDE7 inhibitor, BRL-50481 (BRL), significantly reduced AHR, infiltration of inflammatory cells into the lungs, and the levels of type 2 T helper cell-related cytokines, antigen-specific immunoglobulins, and mucin. Thus, the administration of BRL ameliorated OVA-induced allergic asthmatic responses exacerbated by co-exposure to ASD. This study suggests that PDE7 inhibition can be a therapeutic strategy for inflammatory lung diseases and asthma via the regulation of T lymphocytes and reduction of IL-13, and, consequently, mucin production.

Estimation of the lipophilicity of purine-2,6-dione-based TRPA1 antagonists and PDE4/7 inhibitors with analgesic activity.

Lipophilicity is one of the principal QSAR parameters which influences among others the pharmacodynamics and pharmacokinetic properties of a drug candidates. In this paper, the lipophilicity of 14 amide derivatives of 1,3-dimethyl-2,6-dioxopurin-7-yl-alkylcarboxylic acids as multifunctional TRPA1 channel antagonists and phosphodiesterase 4/7 inhibitors with analgesic activity were investigated, using reversed-phase thin-layer chromatography method. It was observed that the retention behavior of the analyzed compounds was dependent on their structural features i.e. an aliphatic linker length, a kind of substituent at 8 position of purine-2,6-dione scaffold as well as on a substitution in a phenyl group. The experimental parameters (RM0) were compared with computationally calculated partition coefficient values by Principal Component Analysis (PCA). To verify the influence of lipophilic parameter of the investigated compounds on their biological activity the Kruskal-Wallis test was performed. The lowest lipophilicity was observed for the compounds with weak PDE4/7 inhibitory potency. The differences between the lipophilicity of potent inhibitors and inactive compounds were statistically significant. It was found that the presence of more lipophilic propoxy- or butoxy- substituents as well as the elongation of the aliphatic chain to propylene one between the purine-2,6-dione core and amide group were preferable for desired multifunctional activity.

Phosphodiesterase 7(PDE7): A unique drug target for central nervous system diseases.

Phosphodiesterase 7 (PDE7), one of the 11 phosphodiesterase (PDE) families, specifically hydrolyzes cyclic 3', 5'-adenosine monophosphate (cAMP). PDE7 is involved in many important functional processes in physiology and pathology by regulating intracellular cAMP signaling. Studies have demonstrated that PDE7 is widely expressed in the central nervous system (CNS) and potentially related to pathogenesis of many CNS diseases. Here, we summarized the classification and distribution of PDE7 in the brain and its functional roles in the mediation of CNS diseases such as Parkinson's disease (PD), Alzheimer's disease (AD), multiple sclerosis (MS), and schizophrenia. It is expected that the findings collected here will not only lead to a better understanding of the mechanisms by which PDE7 mediates CNS function and diseases, but also aid in the development of novel drugs targeting PDE7 for treatment of CNS diseases.

Circ_0091702 relieves lipopolysaccharide (LPS)-induced cell injury by regulating the miR-182/PDE7A axis in sepsis.

Circular RNA plays an important role in the progression of sepsis. Circ_0091702 has been found to be an important regulator of sepsis progression, so its role and mechanism in sepsis progression deserve to be further explored. Lipopolysaccharide (LPS) could suppress cell viability, while enhance cell apoptosis and inflammation to induce cell injury. Circ_0091702 was downregulated in LPS-induced HK2 cells, and its overexpression alleviated LPS-induced cell injury. MiR-182 could be sponged by circ_0091702. Moreover, miR-182 inhibitor could relieve LPS-induced cell injury, and its overexpression also reversed the inhibition of circ_0091702 on LPS-induced cell injury. PDE7A was a target of miR-182, and its expression was reduced in LPS-induced HK2 cells. Additionally, silencing of PDE7A reversed the suppressive effect of circ_0091702 on LPS-induced cell injury. Our data suggested that circ_0091702 sponged miR-182 to regulate PDE7A, thereby alleviating LPS-induced cell injury in sepsis.

Improved Controlled Release and Brain Penetration of the Small Molecule S14 Using PLGA Nanoparticles.

Phosphodiesterase 7 (PDE7) is an enzyme responsible for the degradation of cyclic adenosine monophosphate (cAMP), an important cellular messenger. PDE7's role in neurotransmission, expression profile in the brain and the druggability of other phosphodiesterases have motivated the search for potent inhibitors to treat neurodegenerative and inflammatory diseases. Different heterocyclic compounds have been described over the years; among them, phenyl-2-thioxo-(1H)-quinazolin-4-one, called S14, has shown very promising results in different in vitro and in vivo studies. Recently, polymeric nanoparticles have been used as new formulations to target specific organs and produce controlled release of certain drugs. In this work, we describe poly(lactic-co-glycolic acid) (PLGA)-based polymeric nanoparticles loaded with S14. Their preparation, optimization, characterization and in vivo drug release profile are here presented as an effort to improve pharmacokinetic properties of this interesting PDE7 inhibitor.

Synthesis and preclinical evaluation of [11C]MTP38 as a novel PET ligand for phosphodiesterase 7 in the brain.

PURPOSE: Phosphodiesterase (PDE) 7 is a potential therapeutic target for neurological and inflammatory diseases, although in vivo visualization of PDE7 has not been successful. In this study, we aimed to develop [11C]MTP38 as a novel positron emission tomography (PET) ligand for PDE7. METHODS: [11C]MTP38 was radiosynthesized by 11C-cyanation of a bromo precursor with [11C]HCN. PET scans of rat and rhesus monkey brains and in vitro autoradiography of brain sections derived from these species were conducted with [11C]MTP38. In monkeys, dynamic PET data were analyzed with an arterial input function to calculate the total distribution volume (VT). The non-displaceable binding potential (BPND) in the striatum was also determined by a reference tissue model with cerebellar reference. Finally, striatal occupancy of PDE7 by an inhibitor was calculated in monkeys according to changes in BPND. RESULTS: [11C]MTP38 was synthesized with radiochemical purity ≥99.4% and molar activity of 38.6 ± 12.6 GBq/µmol. Autoradiography revealed high radioactivity in the striatum and its reduction by non-radiolabeled ligands, in contrast with unaltered autoradiographic signals in other regions. In vivo PET after radioligand injection to rats and monkeys demonstrated that radioactivity was rapidly distributed to the brain and intensely accumulated in the striatum relative to the cerebellum. Correspondingly, estimated VT values in the monkey striatum and cerebellum were 3.59 and 2.69 mL/cm3, respectively. The cerebellar VT value was unchanged by pretreatment with unlabeled MTP38. Striatal BPND was reduced in a dose-dependent manner after pretreatment with MTP-X, a PDE7 inhibitor. Relationships between PDE7 occupancy by MTP-X and plasma MTP-X concentration could be described by Hill's sigmoidal function. CONCLUSION: We have provided the first successful preclinical demonstration of in vivo PDE7 imaging with a specific PET radioligand. [11C]MTP38 is a feasible radioligand for evaluating PDE7 in the brain and is currently being applied to a first-in-human PET study.

A first-in-human study of 11C-MTP38, a novel PET ligand for phosphodiesterase 7.

PURPOSE: Phosphodiesterase 7 (PDE7) is an enzyme that selectively hydrolyses cyclic adenosine monophosphate, and its dysfunction is implicated in neuropsychiatric diseases. However, in vivo visualization of PDE7 in human brains has hitherto not been possible. Using the novel PET ligand 11C-MTP38, which we recently developed, we aimed to image and quantify PDE7 in living human brains. METHODS: Seven healthy males underwent a 90-min PET scan after injection of 11C-MTP38. We performed arterial blood sampling and metabolite analysis of plasma in six subjects to obtain a metabolite-corrected input function. Regional total distribution volumes (VTs) were estimated using compartment models, and Logan plot and Ichise multilinear analysis (MA1). We further quantified the specific radioligand binding using the original multilinear reference tissue model (MRTMO) and standardized uptake value ratio (SUVR) method with the cerebellar cortex as reference. RESULTS: PET images with 11C-MTP38 showed relatively high retentions in several brain regions, including in the striatum, globus pallidus, and thalamus, as well as fast washout from the cerebellar cortex, in agreement with the known distribution of PDE7. VT values were robustly estimated by two-tissue compartment model analysis (mean VT = 4.2 for the pallidum), Logan plot, and MA1, all in excellent agreement with each other, suggesting the reversibility of 11C-MTP38 binding. Furthermore, there were good agreements between binding values estimated by indirect method and those estimated by both MRTMO and SUVR, indicating that these methods could be useful for reliable quantification of PDE7. Because MRTMO and SUVR do not require arterial blood sampling, they are the most practical for the clinical use of 11C-MTP38-PET. CONCLUSION: We have provided the first demonstration of PET visualization of PDE7 in human brains. 11C-MTP38 is a promising novel PET ligand for the quantitative investigation of central PDE7.

Pharmacological inhibition of phosphodiesterase 7 enhances consolidation processes of spatial memory.

Augmentation of cAMP signaling through inhibition of phosphodiesterases (PDE) is known to enhance plasticity and memory. Inhibition of PDE4 enhances consolidation into memory, but less is known about the role of other cAMP specific PDEs. Here, we tested the effects of oral treatment with a selective inhibitor of PDE7 of nanomolar potency on spatial and contextual memory. In an object location task, doses of 0.3-3 mg/kg administered 3 h after training dose-dependently attenuated time-dependent forgetting in rats. Significant enhancement of memory occurred at a dose of 3 mg/kg with corresponding brain levels consistent with PDE7 inhibition. The same dose given prior to training augmented contextual fear conditioning. In mice, daily dosing before training enhanced spatial memory in two different incremental learning paradigms in the Barnes Maze. Drug treated mice made significantly less errors locating the escape in a probe-test 24 h after the end of training, and they exhibited hippocampal-dependent spatial search strategies more frequently than controls, which tended to show serial sampling of escape locations. Acquisition and short-term memory, in contrast, were unaffected. Our data provide evidence for a role of PDE7 in the consolidation of hippocampal-dependent memory. We suggest that targeting PDE7 for memory enhancement may provide an alternative to PDE4 inhibitors, which tend to have undesirable gastrointestinal side-effects.

New imidazopyridines with phosphodiesterase 4 and 7 inhibitory activity and their efficacy in animal models of inflammatory and autoimmune diseases.

Herein, we describe the rapid synthesis of a focused library of trisubstituted imidazo[4,5-b]pyridines and imidazo[4,5-c]pyridines from 2,4-dichloro-3-nitropyridine using the combination of solution-phase/solid-phase chemistry as new potential anti-inflammatory agents in the treatment of autoimmune diseases. Structure-activity relationship studies, followed by the structure optimization, provided hit compounds (17 and 28) which inhibited phosphodiesterase 4 (PDE4) with IC50 values comparable to rolipram and displayed different inhibitory potency against phosphodiesterase 7 (PDE7). Among them, compound 17 showed a beneficial effect in all the studied animal models of inflammatory and autoimmune diseases (concanavalin A-induced hepatitis, lipopolysaccharide-induced endotoxemia, collagen-induced arthritis, and MOG35-55-induced encephalomyelitis). In addition, compound 17 showed a favorable pharmacokinetic profile after intraperitoneal administration; it was characterized by a fast absorption from the peritoneal cavity and a relatively long terminal half-life in rats. It was found to penetrate brain barrier in mice. The performed experiments sheds light on the impact of PDE7A inhibition for the efficacy of PDE4 inhibitors in these disease conditions.

Role of Phosphodiesterase 7 (PDE7) in T Cell Activity. Effects of Selective PDE7 Inhibitors and Dual PDE4/7 Inhibitors on T Cell Functions.

Phosphodiesterase 7 (PDE7), a cAMP-specific PDE family, insensitive to rolipram, is present in many immune cells, including T lymphocytes. Two genes of PDE7 have been identified: PDE7A and PDE7B with three or four splice variants, respectively. Both PDE7A and PDE7B are expressed in T cells, and the predominant splice variant in these cells is PDE7A1. PDE7 is one of several PDE families that terminates biological functions of cAMP-a major regulating intracellular factor. However, the precise role of PDE7 in T cell activation and function is still ambiguous. Some authors reported its crucial role in T cell activation, while according to other studies PDE7 activity was not pivotal to T cells. Several studies showed that inhibition of PDE7 by its selective or dual PDE4/7 inhibitors suppresses T cell activity, and consequently T-mediated immune response. Taken together, it seems quite likely that simultaneous inhibition of PDE4 and PDE7 by dual PDE4/7 inhibitors or a combination of selective PDE4 and PDE7 remains the most interesting therapeutic target for the treatment of some immune-related disorders, such as autoimmune diseases, or selected respiratory diseases. An interesting direction of future studies could also be using a combination of selective PDE7 and PDE3 inhibitors.

Novel anilide and benzylamide derivatives of arylpiperazinylalkanoic acids as 5-HT1A/5-HT7 receptor antagonists and phosphodiesterase 4/7 inhibitors with procognitive and antidepressant activity.

A library of novel anilide and benzylamide derivatives of ω-(4-(2-methoxyphenyl)piperazin-1-yl)alkanoic acids as combined 5-HT1A/5-HT7 receptor ligands and phosphodiesterase PDE4B/PDE7A inhibitors was designed using a structure-based drug design approach. The in vitro studies of 33 newly synthesized compounds (7-39) allowed us to identify 22 as the most promising multifunctional 5-HT1A/5-HT7 receptor antagonist (5-HT1AKi = 8 nM, Kb = 0.04 nM; 5-HT7Ki = 451 nM, Kb = 460 nM) with PDE4B/PDE7A inhibitory activity (PDE4B IC50 = 80.4 µM; PDE7A IC50 = 151.3 µM). Compound 22 exerted a very good ability to passively penetrate through biological membranes and a high metabolic stability in vitro. Moreover, the pharmacological evaluation of 22 showed its procognitive and antidepressant properties in rat behavioral tests. Compound 22 at a dose of 3 mg/kg (i.p.) significantly reversed MK-801-induced episodic memory deficits in the novel object recognition test, while at a dose of 10 mg/kg (i.p.) reduced the immobility time of animals (by about 34%) in the forced swimming test. The antidepressant-like effect produced by compound 22 was stronger than that of escitalopram used as a reference drug. This study opens a new perspective in the search for efficacious drugs for the treatment of cognitive and depressive disorders.