Pharmacological sphingosine-1 phosphate receptor 1 targeting in cigarette smoke-induced emphysema in mice

Protein phosphatase 2A activators under investigation for smoking-related chronic obstructive pulmonary disease and related disorders

INTRODUCTION

Chronic obstructive pulmonary disease (COPD) is characterized by progressive inflammation during therapy. Cystic fibrosis (CF), alpha-one antitrypsin deficiency (AATD), and non-CF bronchiectasis are also chronic respiratory disorders with inflammation and progression that share many similarities with COPD. Therefore, various anti-inflammatory approaches are currently being investigated, and protein phosphatase 2A (PP2A) activators may represent one such approach.

AREAS COVERED

Systematic review of papers published from 2000-to date on the anti-inflammatory role of endogenous PP2A, the consequences of its inhibition by smoking, and the beneficial effects of its activation in COPD.

EXPERT OPINION

PP2A activation is a plausible therapeutic approach in COPD and related disorders, such as CF, AATD, and non-CF bronchiectasis, although the available evidence is still mostly experimental. Metformin repurposing and consideration of inhalation for some of the molecules discussed in this study are promising approaches.

New Therapeutic Options in Pulmonal Diseases: Sphingolipids and Modulation of Sphingolipid Metabolism

Sphingolipids are crucial molecules in the respiratory airways. As in most other tissues and organs, in the lung sphingolipids play an essential role as structural constituents as they regulate barrier function and fluidity of cell membranes. A lung-specific feature is the occurrence of sphingolipids as minor structural components in the surfactant. However, sphingolipids are also key signaling molecules involved in airway cell signaling and their dynamical formation and metabolism are important for normal lung physiology. Dysregulation of sphingolipid metabolism and signaling is involved in altering lung tissue and initiates inflammatory processes promoting the pathogenesis of pulmonal diseases including cystic fibrosis (CF), chronic obstructive pulmonary disease (COPD), and asthma.In the present review, the important role of specific sphingolipid species in pulmonal diseases will be discussed. Only such an understanding opens up the possibility of developing new therapeutic strategies with the aim of correcting the imbalance in sphingolipid metabolism and signaling. Such delivery strategies have already been studied in animal models of these lung diseases, demonstrating that targeting the sphingolipid profile represents new therapeutic opportunities for lung disorders.

The Ying and Yang of Sphingosine-1-Phosphate Signalling within the Bone

Bone remodelling is a highly active and dynamic process that involves the tight regulation of osteoblasts, osteoclasts, and their progenitors to allow for a balance of bone resorption and formation to be maintained. Ageing and inflammation are risk factors for the dysregulation of bone remodelling. Once the balance between bone formation and resorption is lost, bone mass becomes compromised, resulting in disorders such as osteoporosis and Paget's disease. Key molecules in the sphingosine-1-phosphate signalling pathway have been identified for their role in regulating bone remodelling, in addition to its more recognised role in inflammatory responses. This review discusses the accumulating evidence for the different, and, in certain circumstances, opposing, roles of S1P in bone homeostasis and disease, including osteoporosis, Paget's disease, and inflammatory bone loss. Specifically, we describe the current, often conflicting, evidence surrounding S1P function in osteoblasts, osteoclasts, and their precursors in health and disease, concluding that S1P may be an effective biomarker of bone disease and also an attractive therapeutic target for disease.