Compound D159687, a phosphodiesterase 4D inhibitor, induces weight and fat mass loss in aged mice without changing lean mass, physical and cognitive function

PDE4D: A Multipurpose Pharmacological Target

Phosphodiesterase 4 (PDE4) enzymes catalyze cyclic adenosine monophosphate (cAMP) hydrolysis and are involved in a variety of physiological processes, including brain function, monocyte and macrophage activation, and neutrophil infiltration. Among different PDE4 isoforms, Phosphodiesterases 4D (PDE4Ds) play a fundamental role in cognitive, learning and memory consolidation processes and cancer development. Selective PDE4D inhibitors (PDE4Dis) could represent an innovative and valid therapeutic strategy for the treatment of various neurodegenerative diseases, such as Alzheimer's, Parkinson's, Huntington's, and Lou Gehrig's diseases, but also for stroke, traumatic brain and spinal cord injury, mild cognitive impairment, and all demyelinating diseases such as multiple sclerosis. In addition, small molecules able to block PDE4D isoforms have been recently studied for the treatment of specific cancer types, particularly hepatocellular carcinoma and breast cancer. This review overviews the PDE4DIsso far identified and provides useful information, from a medicinal chemistry point of view, for the development of a novel series of compounds with improved pharmacological properties.

Allosteric inhibition of phosphodiesterase 4D induces biphasic memory-enhancing effects associated with learning-activated signaling pathways

RATIONALE

Phosphodiesterase 4D negative allosteric modulators (PDE4D NAMs) enhance memory and cognitive function in animal models without emetic-like side effects. However, the relationship between increased cyclic adenosine monophosphate (cAMP) signaling and the effects of PDE4D NAM remains elusive.

OBJECTIVE

To investigate the roles of hippocampal cAMP metabolism and synaptic activation in the effects of D159687, a PDE4D NAM, under baseline and learning-stimulated conditions.

RESULTS

At 3 mg/kg, D159687 enhanced memory formation and consolidation in contextual fear conditioning; however, neither lower (0.3 mg/kg) nor higher (30 mg/kg) doses induced memory-enhancing effects. A biphasic (bell-shaped) dose-response effect was also observed in a scopolamine-induced model of amnesia in the Y-maze, whereas D159687 dose-dependently caused an emetic-like effect in the xylazine/ketamine anesthesia test. At 3 mg/kg, D159687 increased cAMP levels in the hippocampal CA1 region after conditioning in the fear conditioning test, but not in the home-cage or conditioning cage (i.e., context only). By contrast, 30 mg/kg of D159687 increased hippocampal cAMP levels under all conditions. Although both 3 and 30 mg/kg of D159687 upregulated learning-induced Fos expression in the hippocampal CA1 30 min after conditioning, 3 mg/kg, but not 30 mg/kg, of D159687 induced phosphorylation of synaptic plasticity-related proteins such as cAMP-responsive element-binding protein, synaptosomal-associated protein 25 kDa, and the N-methyl-D-aspartate receptor subunit NR2A.

CONCLUSIONS

Our findings suggest that learning-stimulated conditions can alter the effects of a PDE4D NAM on hippocampal cAMP levels and imply that a PDE4D NAM exerts biphasic memory-enhancing effects associated with synaptic plasticity-related signaling activation.

The Complexity and Multiplicity of the Specific cAMP Phosphodiesterase Family: PDE4, Open New Adapted Therapeutic Approaches

Cyclic nucleotides (cAMP, cGMP) play a major role in normal and pathologic signaling. Beyond receptors, cyclic nucleotide phosphodiesterases; (PDEs) rapidly convert the cyclic nucleotide in its respective 5'-nucleotide to control intracellular cAMP and/or cGMP levels to maintain a normal physiological state. However, in many pathologies, dysregulations of various PDEs (PDE1-PDE11) contribute mainly to organs and tissue failures related to uncontrolled phosphorylation cascade. Among these, PDE4 represents the greatest family, since it is constituted by 4 genes with multiple variants differently distributed at tissue, cellular and subcellular levels, allowing different fine-tuned regulations. Since the 1980s, pharmaceutical companies have developed PDE4 inhibitors (PDE4-I) to overcome cardiovascular diseases. Since, they have encountered many undesired problems, (emesis), they focused their research on other PDEs. Today, increases in the knowledge of complex PDE4 regulations in various tissues and pathologies, and the evolution in drug design, resulted in a renewal of PDE4-I development. The present review describes the recent PDE4-I development targeting cardiovascular diseases, obesity, diabetes, ulcerative colitis, and Crohn's disease, malignancies, fatty liver disease, osteoporosis, depression, as well as COVID-19. Today, the direct therapeutic approach of PDE4 is extended by developing allosteric inhibitors and protein/protein interactions allowing to act on the PDE interactome.

Associations between SNP83 of phosphodiesterase 4D gene and carotid atherosclerosis in a southern Chinese Han population: a case-control study

Atherosclerosis was an important pathophysiological basis of atherothrombotic stroke, and phosphodiesterase 4D (PDE4D) polymorphism (SNP83/rs966221) was reported to be associated with the susceptibility to atherothrombotic stroke. Aim of the present study was to explore the potential association between SNP83 and carotid atherosclerosis (CAS). 204 southern Chinese Han participants were divided into two groups according to the carotid intima-media thickness (IMT) of the carotid artery: CAS group (carotid IMT ≥ 1.0 mm) and non-CAS group (carotid IMT < 1.0 mm). Carotid IMT was measured by color Doppler ultrasound. The PDE4D SNP83 polymorphism was determined by SNaPshot technique. Our study found that SNP83 was associated significantly with CAS susceptibility under the dominant, overdominant and codominant models. After adjusting for age, gender, low-density lipoprotein cholesterol, Hemoglobin A1c, cigarette smoking, hypertension history, and diabetes mellitus history, the association still remained significant (dominant model: crude OR = 2.373, 95% CI: 1.268-4.442, P = 0.007; adjusted OR = 3.129, 95% CI: 1.104-8.866, P = 0.032; overdominant model: crude OR = 1.968, 95% CI: 1.043-3.714, P = 0.037; adjusted OR = 2.854, 95% CI: 1.005-8.108, P = 0.049; codominant: crude OR = 2.102, 95% CI: 1.110-3.979, P = 0.023; adjusted OR = 2.984, 95% CI: 1.047-8.502, P = 0.041). Carotid IMT of carriers with CT + CC genotypes was higher than carriers with TT genotype (P = 0.016). Our results indicated that the SNP83/rs966221 located on PDE4D gene was significantly associated between CAS susceptibility and carotid IMT independently of conventional risk factors in a southern Chinese Han population.

Small Molecules, Big Promises: Improvement of Psoriasis Severity and Glucidic Markers with Apremilast: A Case Report

Psoriasis is a common inflammatory skin condition frequently associated with cardiometabolic diseases such as diabetes. Indeed, the state of systemic inflammation typical of psoriasis leads to an increase in the level of IL-1, IL-6 and TNF-alpha which may cause a reduced sensitivity to insulin and, ultimately, can lead to type 2 diabetes mellitus. Particularly, the derangement of PDE4-cAMP signaling has a critical role in disordered glucose and lipid metabolism. Apremilast, as a selective inhibitor of PDE4-cAMP signalling, represents an innovative therapeutic strategy for psoriasis. Here, we report a case of a patient affected by psoriasis and diabetes, who - after using Apremilast - improved his glucose metabolism as well as his need of anti-diabetic drugs and his psoriasis. This suggests that, in addition to its role against psoriasis, Apremilast may even act as a metabolic modulator.