Actin fence therapy with exogenous V12Rac1 protects against acute lung injury
Galina A. Gusarova, Shonit R. Das, Mohammad N. Islam, Kristin Westphalen, Guangchun Jin, Igor O. Shmarakov, Li Li, Sunita Bhattacharya, Jahar Bhattacharya
Galina A. Gusarova, Shonit R. Das, Mohammad N. Islam, Kristin Westphalen, Guangchun Jin, Igor O. Shmarakov, Li Li, Sunita Bhattacharya, Jahar Bhattacharya
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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

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Figure 5

Protective effects of alveolar F-actin enhancement on ALI.

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Protective effects of alveolar F-actin enhancement on ALI. (A–F) Mice re...
(A–F) Mice received 2 i.n. instillations. The first instillation was a lethal dose of LPS. This was followed by the second instillation, which was PBS, or TAT-conjugated proteins. The second instillation was given 4 (A–C) or 24 (D–F) hours after LPS instillation. The data were obtained 72 hours after LPS for A and B, and at the indicated times for C–G. (A) Bars show BAL phospholipids levels as indicated. Mean ± SEM. *P < 0.05 versus corresponding PBS group using ANOVA with Bonferroni correction. n = 5, except PBS (n = 4). Each dot shows data for a single lung. (B) Bars show lung compliance calculated from the volume-pressure plot. Mean ± SEM. *P < 0.05 using ANOVA with Bonferroni correction. n = 8, except PBS (n = 5). Each dot in bar diagram shows data for a single lung. (C) Kaplan-Meier plots for mouse survival. For each group, n = 12. *P < 0.01 versus LPS + PBS using log-rank test. (D and E) Data were obtained 48 hours after LPS. Bars show blood-free extravascular lung water (EVLW) (D) and total leukocyte count in BAL (E). Mean ± SEM. *P < 0.001 using ANOVA with Bonferroni correction. n = 4, except TAT-N17Rac1 in D (n = 3). Each dot shows data for a single lung. Baseline values shown as dashed line. (F) Kaplan-Meier plots for mouse survival after LPS. For each group, n = 8. *P < 0.01 versus LPS + PBS using log-rank test. (G) Kaplan-Meier plots for mouse survival after instillation of P. aeruginosa (PA), followed 4 hours later by TAT-Rac1 proteins. For each group, n = 5. *P < 0.01 versus PA + PBS using log-rank test.