Expression of phosphodiesterase 3 in rat submandibular gland cell lines

Advancing Obstructive Airway Disease Treatment: Dual PDE3/4 Inhibition as a Therapeutic Strategy

Obstructive airway diseases, including asthma and chronic obstructive pulmonary disease (COPD), evoke significant global health concerns manifested by airway inflammation and obstruction. Despite their differing origins, shared pathophysiological features and responses to therapeutic interventions highlight common molecular mechanisms. Standard treatments include inhaled bronchodilators, with combination therapies offering enhanced symptom control. Cyclic AMP (cAMP) plays a crucial role in airway relaxation. Phosphodiesterase (PDE) decreases cAMP levels, thereby attenuating the relaxation of airway smooth muscle, making it a promising therapeutic target. The balance between cAMP production and degradation is essential for regulating airway tone and function. PDE inhibitors for the treatment of obstructive airway diseases have suffered challenges, with adverse side effects of prospective inhibitors causing clinical failures. Efforts to develop PDE inhibitors with an improved safety profile could prove to be beneficial as an add-on treatment for severe asthma and COPD. The recent FDA approval of Ensifentrine, a dual PDE3/4 inhibitor, can significantly advance COPD management by improving bronchodilation, reducing inflammation, and lowering exacerbation rates with favorable safety outcomes.

Reengineering salivary gland cells to enhance protein secretion for use in developing artificial salivary gland device

Salivary glands (SGs) are considered exocrine glands, which mainly secrete water into the oral cavity. Nevertheless, they also exhibit a smaller endocrine secretory pathway toward the bloodstream. The concept of an artificial SG device for exocrine fluid secretion into the oral region in xerostomic patients has been previously studied. The purpose of the current study was to examine the potential of such a device for enhancing bioactive protein secretion. We engineered a plasmid encoding a SG-specific signal peptide sequence adjacent to a normally nonsecreted encoded reporter gene creating a chimera protein, and examined if this construct can enhance secretion from salivary epithelial cells. An N-terminal encoding epidermal growth factor (EGF) sequence was synthesized and inserted into a pGL3 control vector 5' of a firefly luciferase gene, creating a pGL3-EGF signal peptide (pGL3-EGFSP) fused vector. This vector was cotransfected with a pRL-CMV vector containing a Renilla luciferase gene, in 293 cells (serving as controls), and human submandibular gland ductal epithelial (HSG), rat submandibular gland acinar epithelial (SMIE), and rat submandibular gland ductal epithelial (A5) salivary cell lines. The transfected 293, SMIE, and HSG cells showed 8-, 18-, and 40-fold higher luciferase activity, respectively. These observations lead to the concept of an envisioned secretory device, which can serve as a potential biological pump for bioactive proteins.

Expression of cyclic nucleotide phosphodiesterase 3A in isolated rat submandibular acini

Phosphodiesterase (PDE) 3 has been characterized in isolated rat submandibular acini. PDE3 activity was detected in homogenates of isolated rat submandibular acini; little or no PDE3 activity was found in ducts. About 62% of PDE3 activity in the acini was recovered in the supernatant fractions; 38% in particulate fractions. In the acini, but not ducts, PDE3A mRNA was detected by reverse transcriptase-polymerase chain reaction (RT-PCR). The PDE3-specific inhibitor, cilostamide, increased the ratio of apomucin mRNA/18s rRNA, as quantified by real-time RT-PCR. Our results indicate that PDE3A may be important in regulating cAMP pools that control acini functions.