The Effects of a Transgelin-2 Agonist Administered at Different Times in a Mouse Model of Airway Hyperresponsiveness

Abstract

Airway hyperresponsiveness (AHR) is one of the most important features of asthma. Our previous study showed that inhaled transgelin-2 agonist, TSG12, effectively reduced pulmonary resistance in a mouse model of asthma in a dose-dependent manner. However, the optimal administration time of TSG12 to reduce AHR and the pharmacological effects are still unclear. In this study, the effects of TSG12 inhalation before and during AHR occurrence were examined. The results showed that the pulmonary resistance was reduced by 57% and the dynamic compliance was increased by 46% in the TSG12 Mch group (atomize TSG12 10 min before methacholine, p < 0.05 vs. model). The pulmonary resistance was reduced by 61% and the dynamic compliance was increased by 47% in the TSG12 + Mch group (atomize TSG12 and methacholine together, p < 0.05 vs. model). Quantitative real-time PCR showed that the gene expression levels of transgelin-2, myosin phosphatase target subunit-1, and myosin light chain were up-regulated by 6.4-, 1.9-, and 2.8-fold, respectively, in the TSG12 Mch group. The gene expression levels of transgelin-2, myosin phosphatase target subunit-1, and myosin light chain were up-regulated by 3.2-, 1.4-, and 1.9-fold, respectively, in the TSG12 + Mch group. The results suggested that TSG12 effectively reduces pulmonary resistance when TSG12 inhalation occurred both before and during AHR occurrence. Gene expression levels of transgelin-2 and myosin light chain were significantly up-regulated when TSG12 inhalation occurred before AHR occurrence. This study may provide a basis for the administration time of TSG12 for asthma treatment in the future.

Keywords: TSG12; administration time; agonist; airway hyperresponsiveness; asthma; transgelin-2.

FIGURE 1

Schematic of administration. The Mch group was administered with atomized NS at 0 min and Mch at 10 min. The TSG12 + Mch group was atomized with NS at 0 min and TSG12 together with Mch at 10 min. The TSG12 Mch group was atomized with NS at 0 min, TSG12 at 10 min, and Mch at 20 min. The TB + Mch group was atomized with NS at 0 min and TB together with Mch at 10 min. The TB Mch group was atomized at 0 min, TB at 10 min, and Mch at 20 min. Abbreviations: NS, normal saline; Mch, methacholine; TB, terbutaline.

FIGURE 2

Changes in pulmonary resistance and dynamic compliance in mice with AHR. (A) RL increased 40-fold after stimulation with Mch (vs. blank). RL was reduced by 57% in the TSG12 Mch group and reduced by 61% in the TSG12 + Mch group (vs. Mch). (B) Cdyn was reduced 14-fold after stimulation with Mch (vs. blank). Cdyn was increased by 46% in the TSG12 Mch group and increased by 47% in the TSG12 + Mch group (vs. Mch). Data were presented as the mean ± SEM, N = 6, P<0.05 was considered statistically significant. Abbreviations: Cdyn, dynamic compliance; Mch, methacholine; RL, pulmonary resistance; SEM, standard error of mean.

FIGURE 3

Histopathological lung changes among different groups. (A) In the blank group, the bronchiolar structure (red arrow) was clear and there was no inflammatory cell infiltration around the bronchiolar (blue arrow). In the Mch group, TSG12 + Mch group, and TSG12 Mch group, there were no significant changes compared with the blank group. (B) Inflammation scores among different groups. Data were presented as the mean ± SEM, N = 6, P<0.05 was considered statistically significant. Abbreviations: Mch, methacholine; SEM, standard error of mean.

FIGURE 4

Expression of relevant genes after TSG12 administration. (A) Expression levels of transgelin-2 were up-regulated by 1.4-, 3.2-, and 6.1-fold in the Mch group, TSG12 + Mch group, and TSG12 Mch group, respectively (vs. blank). (B) Expression levels of MYPT1 were up-regulated by 2.1-, 1.4-, and 1.9-fold in the Mch group, TSG12 + Mch group, and TSG12 Mch group, respectively (vs. blank). (C) Expression levels of MLC were up-regulated by 1.1-, 1.9-, and 2.8-fold in the Mch group, TSG12 + Mch group, and TSG12 Mch group, respectively (vs. blank). Values were presented by the 2^−ΔΔCt method, N = 6, changes with a 2-fold increase in expression were considered to be up-regulated, and changes with a 0.5-fold decrease in expression were considered to be down-regulated. Abbreviations: Mch, methacholine; MYPT1, myosin phosphatase target subunit-1; MLC, myosin light chain.