Hwang JJ, et al. J Korean Med Sci. 2020 Jan;35(5):e35. https://doi.org/10.3346/jkms.2020.35.e35

Lung injury is characterized by diffuse lung inflammation, alveolar-capillary destruction, and alveolar flooding, resulting in respiratory failure. Polydexyribonucleotide (PDRN) has an anti-inflammatory effect, decreasing inflammatory cytokines, and suppressing apoptosis. Thus, we investigated its efficacy in the treatment of lung injury, which was induced in rats using lipopolysaccharide (LPS). Rats were randomly divided into three groups according to sacrifice time, and each group split into control, lung injury-induced, and lung injury-induced + PDRN-treated groups. Rats were sacrificed 24 h and 72 h after PDRN administration, according to each group. Lung injury was induced by intratracheal instillation of LPS (5 mg/kg) in 0.2 mL saline. Rats in PDRN-treated groups received a single intraperitoneal injection of 0.3 mL distilled water including PDRN (8 mg/kg), 1 h after lung injury induction. Percentages of terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL)-positive, cleaved caspase-3-, -8-, and -9-positive cells, the ratio of Bcl-2-associated X protein (Bax) to B-cell lymphoma 2 (Bcl-2), and expressions of inflammatory cytokines (tumor necrosis factor-α, interleukin-6) were decreased by PDRN treatment in the LPS-induced lung injury rats. Therefore, treatment with PDRN reduced lung injury score. This anti-apoptotic effect of PDRN can be ascribed to the enhancing effect of PDRN on adenosine A_2A receptor expression. Based on these results, PDRN might be considered as a new therapeutic agent for the treatment of lung injury.

Purpose: Inhalation of air containing high amounts of particular matter (PM) causes various respiratory disorders including asthma, chronic obstructive pulmonary disease, and lung cancer. The changes of expression of inflammatory factors by polydeoxyribonucleotide (PDRN) administration in the PM10-exposed trachea inflammation model were evaluated.Methods: PM10 was administered to mouse trachea to induce acute inflammatory damage, and changes in inflammatory factors were observed after administration of PDRN and 3,7-dimethyl-1-propargylxanthine (DMPX) for 3 days daily. Expression of inflammatory cytokines, adenosine A2A receptor (A2AR), protein kinase A (PKA), 3΄,5΄-cyclic adenosine monophosphate responsive element binding protein (CREB) were detected by enzyme‐linked immunosorbent assay, immunofluorescence, and western blot assay.Results: PM-exposed trachea showed increased tumor necrosis factor (TNF)-α and interleukin (IL)-1β expression, and expression of TNF-α and IL-1β was inhibited by PDRN treatment in PM-exposed mice. PM-exposed trachea showed increased nuclear factor (NF)-κB phosphorylation, and phosphorylation of nuclear factor-kappa B was inhibited by PDRN treatment in PM-exposed mice. PM-exposed trachea showed increased expression of A2AR, but PDRN treatment more enhanced A2AR expression in PM-exposed mice. PKA phosphorylation was not changed and CREP phosphorylation was decreased, however PDRN treatment increased phosphorylation of PKA and CREB in PM-exposed mice. DMPX treatment blocked all the effects of PDRN on PM-exposed mice, demonstrating that the action of PDRN occurs via A2AR.Conclusions: PDRN treatment attenuated inflammation in the trachea of the PM10-exposed mice. This improving effect of PDRN can be ascribed to the activation of A2AR through the cAMP-PKA pathway.

Purpose: Acute respiratory distress syndrome (ARDS) is characterized by its acute onset of symptoms such as bilateral pulmonary infiltrates, severe hypoxemia, and pulmonary edema. Many patients with ARDS survive in the acute phase, but then die from significant lung fibrosis.Methods: The effect of combination therapy with polydeoxyribonucleotide (PDRN) and pirfenidone on ARDS was investigated using human lung epithelial A549 cells. ARDS environment was induced by treatment with lipopolysaccharide and transforming growth factor (TGF)-β. Enzyme-linked immunoassay for connective tissue growth factor (CTGF) and hydroxyproline were conducted. Western blot for collagen type I, fibroblast growth factor (FGF), tumor necrosis factor (TNF)-α, and interleukin (IL)-6 was performed.Results: In this study, 8-μg/mL PDRN enhanced cell viability. Combination therapy with PDRN and pirfenidone and pirfenidone monotherapy suppressed expressions of CTGF and hydroxyproline and inhibited expressions of collagen type I and FGF. Combination therapy with PDRN and pirfenidone and PDRN monotherapy suppressed expression of TNF-α and IL-1β.Conclusions: The combination therapy with PDRN and pirfenidone exerted stronger therapeutic effect against lipopolysaccharide and TGF-β-induced ARDS environment compared to the PDRN monotherapy or pirfenidone monotherapy. The excellent therapeutic effect of combination therapy with PDRN and pirfenidone on ARDS was shown by promoting the rapid anti-inflammatory effect and inhibiting the fibrotic processes.

Respiratory symptoms are prevalent in the general population, and they are associated with a decline in lung function and increased mortality. The gut–lung connection suggests intestinal dysbiosis may impact lung diseases, with Akkermansia muciniphila showing promise in regulating extraintestinal diseases. However, its application in patients with respiratory symptoms lacks clinical trial evidence. In this randomized, double-blind trial, ETB-F01, containing heat-killed A. muciniphila strain EB-AMDK19, was compared with a placebo in patients experiencing respiratory symptoms for 4 to 12 weeks. The primary outcome was improvement in Breathlessness, Cough, and Sputum Scale (BCSS) score over 12 weeks. Secondary outcomes included lung function, fractional exhaled nitric oxide (FeNO), modified Medical Research Council (mMRC) dyspnea scale, St. George’s Respiratory Questionnaire (SGRQ), and Visual Analog Scale (VAS) score. The primary analysis was performed in the per-protocol set, with a sensitivity analysis in the full analysis set. In the per-protocol population, 68 participants were randomly assigned to the ETB-F01 group and 65 to the placebo group. ETB-F01 had a superior efficacy over placebo in improving BCSS total scores (between-group difference = −0.8 (95% confidence interval, −1.4–−0.3), p-value = 0.004). Specifically, there was a significant reduction in BCSS breathlessness and cough domain scores with ETB-F01. While trends toward improvement in lung function were noted, statistical significance was not achieved. No significant differences were observed in FeNO and other symptom scores (mMRC, SGRQ, and VAS). In safety profile, ETB-F01 did not cause any serious adverse events. These results suggest that ETB-F01 is safe and effective for alleviating respiratory symptoms.