Phosphatidylinositol 5-Phosphate-Loaded Apoptotic Body-Like Liposomes for Mycobacterium abscessus Infection Management in Patients With Cystic Fibrosis

Abstract

The study investigates therapeutic strategies for managing chronic Mycobacterium abscessus infections, particularly in people with cystic fibrosis (PWCF) who are ineligible for standard elexacaftor, tezacaftor, ivakaftor (ETI) treatments. Apoptotic body-like liposomes loaded with phosphatidylinositol 5-phosphate (ABL/PI5P) were tested in vitro in M. abscessus-infected macrophages from PWCF as potential treatment. ABL/PI5P reduced intracellular bacterial viability and showed enhanced effects on a M. abscessus clinical strain when combined with amikacin. Notably, ABL/PI5P was effective on macrophages from PWCF not receiving ETI therapy. The findings suggest ABL/PI5P liposomes as a promising alternative or adjunct therapy, especially for those who cannot access ETI treatment, warranting further clinical investigation.

Keywords: Mycobacterium abscessus; ETI; cystic fibrosis; host-directed therapy; innate immunity; liposomes; pathogen-directed therapy; phosphatidylinositol 5-phosphate.

Figure 1.

ABL/PI5P reduces Mycobacterium abscessus intracellular viability in macrophages from PWCF irrespective of ETI therapeutic regimen eligibility. Monocyte-derived macrophages from PWCF under an ETI regimen (n = 15) (A) or from PWCF without a modulator regimen (n = 15) (B) were cultured at a concentration of 1 × 10⁶ cells/mL in 96-well plates. Cells were then infected with M. abscessus at multiplicity of infection 10 for 3 hours and finally stimulated with ABL/PI5P and/or ETI for 18 hours. Replication index was calculated as the ratios between the colony-forming units obtained after 18 hours from infection, in the presence or absence of stimuli, and those obtained immediately after infection. For a deeper analysis of the results, patients with CF represented in (B) were divided into 2 groups: (C) those eligible (n = 8) and (D) not eligible (n = 7) for the ETI therapeutic regimen. The results are shown as mean ± standard deviation of the values obtained. Statistical analysis was performed by 2-sided Wilcoxon matched-pairs signed rank test. *P < .05, **P < .01 ***P < .001, ****P < .0001. If not indicated by the line, the comparisons were performed versus control. Abbreviations: ABL/PI5P, apoptotic body-like liposome/phosphatidylinositol 5-phosphate; PWCF, people with cystic fibrosis; ETI, elexacaftor, tezacaftor, ivacaftor; ns, not significant.

Figure 2.

ABL/PI5P-amikacin combined treatment reduces Mab285 intracellular viability in macrophages of PWCF who do not receive ETI therapeutic regimen. MDM from PWCF without a modulator regimen (n = 6) were cultured at a concentration of 1 × 10⁶ cells/mL in 96-well plates. Cells were then infected with Mycobacterium abscessus at multiplicity of infection 10 for 3 hours and stimulated with ABL/PI5P and/or 4 µg/mL amikacin for 18 hours. Finally, supernatant was collected, and MDM were lysed to enumerate extracellular (A) and intracellular (B) bacteria. Replication index was calculated as the ratio between the colony-forming units obtained 18 hours after infection in the presence or absence of ABL/PI5P and/or amikacin, and those obtained immediately after infection and before the stimuli. The results are shown as mean ± standard deviation of the values obtained. Statistical analysis was performed by 2-sided Wilcoxon matched-pairs signed rank test. *P < .05. If not indicated by the line, the comparisons were performed versus control. Abbreviations: ABL/PI5P, apoptotic body-like liposome/phosphatidylinositol 5-phosphate; PWCF, people with cystic fibrosis; ETI, elexacaftor, tezacaftor, ivacaftor; MDM, monocyte-derived macrophages; ns, not significant.