Actin fence therapy with exogenous V12Rac1 protects against acute lung injury
Galina A. Gusarova, … , Sunita Bhattacharya, Jahar Bhattacharya
Galina A. Gusarova, … , Sunita Bhattacharya, Jahar Bhattacharya
Published March 22, 2021
Citation Information: JCI Insight. 2021;6(6):e135753. https://doi.org/10.1172/jci.insight.135753.
View: Text | PDF
Research Article Pulmonology

Actin fence therapy with exogenous V12Rac1 protects against acute lung injury

Abstract

High mortality in acute lung injury (ALI) results from sustained proinflammatory signaling by alveolar receptors, such as TNF-α receptor type 1 (TNFR1). Factors that determine the sustained signaling are not known. Unexpectedly, optical imaging of live alveoli revealed a major TNF-α–induced surge of alveolar TNFR1 due to a Ca2+-dependent mechanism that decreased the cortical actin fence. Mouse mortality due to inhaled LPS was associated with cofilin activation, actin loss, and the TNFR1 surge. The constitutively active form of the GTPase, Rac1 (V12Rac1), given intranasally (i.n.) as a noncovalent construct with a cell-permeable peptide, enhanced alveolar filamentous actin (F-actin) and blocked the TNFR1 surge. V12Rac1 also protected against ALI-induced mortality resulting from i.n. instillation of LPS or of Pseudomonas aeruginosa. We propose a potentially new therapeutic paradigm in which actin enhancement by exogenous Rac1 strengthens the alveolar actin fence, protecting against proinflammatory receptor hyperexpression, and therefore blocking ALI.

Authors

Galina A. Gusarova, Shonit R. Das, Mohammad N. Islam, Kristin Westphalen, Guangchun Jin, Igor O. Shmarakov, Li Li, Sunita Bhattacharya, Jahar Bhattacharya

×

Figure 4

Effects of Rac1 mutants on alveolar F-actin and TNFR1 expression after LPS.

Options: View larger image (or click on image) Download as PowerPoint
Effects of Rac1 mutants on alveolar F-actin and TNFR1 expression after L...
Mice were given 2 i.n. instillations each, as indicated. Mice were separately given a first instillation of PBS, TAT-V12Rac1, or N17-Rac1. In each mouse, a second instillation of PBS or LPS (sublethal dose) was given after 30 minutes. Data were obtained 24 hours after LPS. (A) Confocal images show alveolar immunofluorescence of TNFR1 (red) and of neutrophils, detected by Ly6G immunofluorescence (green) after indicated treatments. Abs were microinjected in alveoli. Scale bar: 50 μm. Alv, alveolus. Replicated in 3 lungs for each group. (B and C) Bars show the total leukocyte count in BAL (B) and alveolar permeability to albumin (C). OD, optical density of Evans blue–bound albumin. n = 4 mice in PBS treated groups, n = 5 mice in LPS treated groups. (D–G) Lung immunoblots and densitometry are for indicated proteins for total lung lysates, and for triton-insoluble (F-actin) and -soluble (G-actin) fractions of lung lysates. Alveolar, streptavidin pulldown of epithelium biotinylated in situ. Data are presented as mean ± SEM. Each dot shows data for a single lung. n = 5-6 except in G, as indicated by the dots. *P < 0.05 as indicated using ANOVA with Bonferroni correction.