Role of the extracellular signal-regulated kinase 1/2 signaling pathway in regulating the secretion of bronchial smooth muscle cells in a rat model of chronic asthma:

Clinical efficacy of recombinant human latrophilin 3 antibody in the treatment of pediatric asthma

Pediatric asthma is a chronic pulmonary inflammatory disease featuring hypersecretion of mucus and inflammation in the airway, resulting in dysfunction of the airway smooth muscle. Previous evidence demonstrated that latrophilins, a novel family of receptors, present a beneficial effect on airway smooth muscle cells. In the present study, the therapeutic effects of recombinant human latrophilin 3 (rhLPHN3) antibody (Ab) in patients with pediatric asthma were investigated, and the molecular mechanism underlying the function of LPHN3 in the treatment of asthma in clinical practice was examined. A total of 342 pediatric asthma cases were recruited and randomly divided into three groups, receiving treatment with rhLPHN3 Ab (n=134), salbutamol (n=108) or montelukast (n=100) by nasal aerosolization. Each group received the respective clinically tested dose for 16 weeks. Inflammatory factors interleukin (IL)-10, IL-17, IL-4, matrix metallopeptidase-9 (MMP-9), interferon-γ (IFN-γ) and transforming growth factor-β (TGF-β) levels in peripheral blood mononuclear cells were analyzed prior to and post treatment. The clinical outcomes revealed that pathological alterations were significantly improved following treatment with rhLPHN3 Ab for patients with pediatric asthma when compared with those receiving salbutamol and montelukast. It was also observed that rhLPHN3 Ab downregulated the plasma concentration levels of IL-10, IL-17, IL-4 and MMP-9, and upregulated IFN-γ and TGF-β levels in the three groups. In addition, clinical data demonstrated that rhLPHN3 Ab significantly promoted E-selectin and mucin 5AC expression, as well as improved the activation of nuclear factor (NF)-κB p65 DNA binding activity and the phosphorylation levels of protein kinase A. Furthermore, rhLPHN3 Ab markedly improved adhesion and proliferation of airway smooth muscle cells, which led to promotion of the contraction of these cells. In conclusion, these clinical data suggest that rhLPHN3 Ab serves an important role in the inhibition of inflammatory mediators through downregulation of NF-κB signaling pathway, which contributes to airway remodeling and bronchodilation in patients with pediatric asthma.

Role of the extracellular signal-regulated kinase 1/2 signaling pathway in the process of thrombin-promoting airway remodeling in ovalbumin-allergic rats

CONTEXT

Although it is recognized that thrombin plays a key role in airway remodeling during chronic asthma. In a previous study, we have proved that thrombin promotes airway remodeling via PAR-1 in OVA-allergic rats, but little is known about intracellular signaling pathway involved in the event.

OBJECTIVE

In this study, we intend to explore the impact of pERK1/2 signaling pathway on the process of thrombin-induced airway remodeling in OVA-allergic rats.

MATERIALS AND METHODS

A rat model of chronic asthma was set up by systemic sensitization and repeated challenge to OVA. The doses of thrombin, recombinant hirudin, PAR-1 inhibitor ER-112780-06, and pERK1/2 inhibitor PD98059 varied for different groups. The expression of pERK1/2 was analyzed by western blot and RT-PCR. Secretion of TGF-β1 and IL-6 was detected by ELISA.

RESULTS

The expression of pERK1/2 was higher in the airway of asthmatic rats than those of normal rats, and was significantly increased by thrombin treatment but decreased by thrombin-inhibitor treatment. Airway remodeling was enhanced by thrombin but weakened by pERK1/2 inhibitor. Expression of growth factors and IL-6 in asthmatic rats was significantly increased by thrombin treatment and decreased by thrombin-inhibitor treatment and pERK1/2 inhibitor treatment.

CONCLUSION

These results suggest that ERK1/2 signaling pathway may play an important role in the process of thrombin-promoting airway remodeling in OVA-allergic rats, and pERK1/2 inhibitor effectively inhibits the process.

Targeting TGFβ superfamily ligand accessory proteins as novel therapeutics for chronic lung disorders

Dysregulation of the transforming growth factor β (TGFβ) pathway has been implicated to underlie a number of disease indications including chronic lung disorders such as asthma, chronic obstructive pulmonary disease (COPD), interstitial pneumonias, and pulmonary arterial hypertension (PAH). Consequently, the pharmaceutical industry has devoted significant resources in the pursuit of TGFβ pathway inhibitors that target the cognate type I and II receptors and respective ligands. The progress of these approaches has been painfully slow, due in part to dose-limiting safety issues that result from the antagonism of a pathway that is responsible for regulating many fundamental biological processes including immune surveillance and cardiovascular responses. These disappointments have led many in the field to conclude that modulating the TGFβ pathway for chronic indications with a sufficient safety window using conventional approaches may be extremely difficult to achieve. Here we review the rationale and limitations of the use of TGFβ pathway inhibitors in chronic lung disorders and the possibility of targeting TGFβ superfamily ligand accessory proteins to allow rheostatic regulation of signaling to achieve efficacy while maintaining a sufficient therapeutic index.

Anti-inflammatory role of the cAMP effectors Epac and PKA: implications in chronic obstructive pulmonary disease

Cigarette smoke-induced release of pro-inflammatory cytokines including interleukin-8 (IL-8) from inflammatory as well as structural cells in the airways, including airway smooth muscle (ASM) cells, may contribute to the development of chronic obstructive pulmonary disease (COPD). Despite the wide use of pharmacological treatment aimed at increasing intracellular levels of the endogenous suppressor cyclic AMP (cAMP), little is known about its exact mechanism of action. We report here that next to the β(2)-agonist fenoterol, direct and specific activation of either exchange protein directly activated by cAMP (Epac) or protein kinase A (PKA) reduced cigarette smoke extract (CSE)-induced IL-8 mRNA expression and protein release by human ASM cells. CSE-induced IκBα-degradation and p65 nuclear translocation, processes that were primarily reversed by Epac activation. Further, CSE increased extracellular signal-regulated kinase (ERK) phosphorylation, which was selectively reduced by PKA activation. CSE decreased Epac1 expression, but did not affect Epac2 and PKA expression. Importantly, Epac1 expression was also reduced in lung tissue from COPD patients. In conclusion, Epac and PKA decrease CSE-induced IL-8 release by human ASM cells via inhibition of NF-κB and ERK, respectively, pointing at these cAMP effectors as potential targets for anti-inflammatory therapy in COPD. However, cigarette smoke exposure may reduce anti-inflammatory effects of cAMP elevating agents via down-regulation of Epac1.