Acinetobacter baumannii thrives within eukaryotic cells, influencing persistence, treatment approaches, and progression of disease. We probed epithelial cell invasion by A. baumannii and the influence of antibodies raised to outer membrane protein 34 (Omp34) on epithelial interactions. We expressed and purified recombinant Omp34 and induced anti-Omp34 antibodies in Bagg albino or BALB/c mice. Omp34 was evaluated for acute toxicity in mice through histological analysis of six organs. The host cell line, A549, was exposed to both A. baumannii 19606 and a clinical isolate. The study also investigated serum resistance, adherence, internalization, and proliferation of A. baumannii in A549 cells, with and without anti-Omp34 sera, utilizing cell culture techniques and light microscopy. A549 cell viability was evaluated by A. baumannii challenge and exposure to anti-Omp34 sera. Actin disruption experiments using cytochalasin D probed microfilament and microtubule roles in A. baumannii invasion. Omp34 prompted antibody production without toxicity in mice. The serum showed bactericidal effects on both strains. Additionally, both A. baumannii strains were found to form biofilms. Omp34 serum was observed to decrease biofilm formation, bacterial adherence, internalization, and proliferation in A549 cells. Furthermore, the use of anti-Omp34 serum enhanced the post-infection survival of the host cell. Pre-exposure of A549 cells to cytochalasin D reduced bacterial internalization, highlighting the role of actin polymerization in the invasion process. Microscopic analysis revealed various interactions, such as adherence, membrane alterations, vacuolization, apoptosis, and cellular damage. Anti-Omp34 serum-exposed A549 cells were protected and showed reduced damage. The findings reveal that A. baumannii can significantly multiply intracellularly within host cells. This suggests the bacterium's ability to establish an environment conducive to its replication by preventing fusion with degradative lysosomes and inhibiting acidification. This finding contributes to the understanding of A. baumannii's intracellular persistence and highlights the role of Omp34 in influencing apoptosis, autophagy, and bacterial adherence, which may impact the development of effective treatments against A. baumannii infections.

Department of Biology and Molecular Microbiology Research Center Shahed University Tehran Qom Expressway Tehran 3319118651 Iran

Department of Biology Shahed University Tehran Iran

Department of Pathology School of Medicine Shahed University Tehran Iran

Zobrazit více v PubMed

Ahmad TA, Tawfik DM, Sheweita SA, Haroun M, El-Sayed LH (2016) Development of immunization trials against Acinetobacter baumannii. Trials Vaccinol 5:53–60. https://doi.org/10.1016/j.trivac.2016.03.001 DOI

Ambrosi C, Scribano D, Sarshar M, Zagaglia C, Singer BB, Palamara AT (2020) Acinetobacter baumannii targets human carcinoembryonic antigen-related cell adhesion molecules (CEACAMs) for invasion of pneumocytes. mSystems 510.1128/mSystems.00604–20

An Z, Su J (2019) Acinetobacter baumannii outer membrane protein 34 elicits NLRP3 inflammasome activation via mitochondria-derived reactive oxygen species in RAW264.7 macrophages. Microbes Infect 21:143–153. https://doi.org/10.1016/j.micinf.2018.10.005 PubMed DOI

An Z, Huang X, Zheng C, Ding W (2019) Acinetobacter baumannii outer membrane protein A induces HeLa cell autophagy via MAPK/JNK signaling pathway. Int J Med Microbiol 309:97–107. https://doi.org/10.1016/j.ijmm.2018.12.004 PubMed DOI

Barati H, Fekrirad Z, Jalali Nadoushan M, Rasooli I (2024) Anti-OmpA antibodies as potential inhibitors of Acinetobacter baumannii biofilm formation, adherence to, and proliferation in A549 human alveolar epithelial cells. Microb Pathogenesis 186:106473. https://doi.org/10.1016/j.micpath.2023.106473 DOI

Cano DA, Martı́nez-Moya M, Pucciarelli MG, Groisman EA, Casadesús J, Garcı́a-Del Portillo F (2001) Salmonella enterica serovar Typhimurium response involved in attenuation of pathogen intracellular proliferation. Infect Immun 69:6463–6474. https://doi.org/10.1128/iai.69.10.6463-6474.2001 PubMed DOI PMC

Choi CH, Lee JS, Lee YC, Park TI, Lee JC (2008) Acinetobacter baumannii invades epithelial cells and outer membrane protein A mediates interactions with epithelial cells. BMC Microbiol 8:216. https://doi.org/10.1186/1471-2180-8-216 PubMed DOI PMC

Cook-Libin S, Sykes EME, Kornelsen V, Kumar A (2022) Iron acquisition mechanisms and their role in the virulence of Acinetobacter baumannii. Infect Immun 90:e00223–e00222. https://doi.org/10.1128/iai.00223-22 PubMed DOI PMC

Fereshteh S, Goodarzi NN, Sepehr A, Shafiei M, Ajdary S, Badmasti F (2022) In silico analyses of extracellular proteins of Acinetobacter baumannii as immunogenic candidates. Iran J Pharm Res. https://doi.org/10.5812/ijpr-126559 PubMed DOI PMC

Gaddy JA, Tomaras AP, Actis LA (2009) The Acinetobacter baumannii 19606 OmpA protein plays a role in biofilm formation on abiotic surfaces and in the interaction of this pathogen with eukaryotic cells. Infect Immun 77:3150–3160. https://doi.org/10.1128/iai.00096-09 PubMed DOI PMC

Garcia-Quintanilla M, Pulido RM, McConnell JM (2013) First steps towards a vaccine against Acinetobacter baumannii. Curr Pharm Biotechno 14:897–902. https://doi.org/10.2174/1389201014666131226123511 DOI

Huang W, Yao Y, Wang S, Xia Y, Yang X, Long Q, Sun W, Liu C, Li Y, Chu X, Bai H, Yao Y, Ma Y (2016) Immunization with a 22 kDa outer membrane protein elicits protective immunity to multidrug-resistant Acinetobacter baumannii. Sci Rep 6:20724. https://doi.org/10.1038/srep20724 PubMed DOI PMC

Kennedy DA, Read AF (2017) Why does drug resistance readily evolve but vaccine resistance does not? P Roy Soc B-Biol Sci 284:20162562. https://doi.org/10.1098/rspb.2016.2562 DOI

Kim J, Lee JY, Lee H, Choi JY, Kim DH, Wi YM, Peck KR, Ko KS (2017) Microbiological features and clinical impact of the type VI secretion system (T6SS) in Acinetobacter baumannii isolates causing bacteremia. Virulence 8:1378–1389. https://doi.org/10.1080/21505594.2017.1323164 PubMed DOI PMC

Lázaro-Díez M, Navascués-Lejarza T, Remuzgo-Martínez S, Navas J, Icardo JM, Acosta F, Martínez-Martínez L, Ramos-Vivas J (2016) Acinetobacter baumannii and A. pittii clinical isolates lack adherence and cytotoxicity to lung epithelial cells in vitro. Microbes Infect 18:559–564. https://doi.org/10.1016/j.micinf.2016.05.002 PubMed DOI

Lee JC, Koerten H, van den Broek P, Beekhuizen H, Wolterbeek R, van den Barselaar M, van der Reijden T, van der Meer J, van de Gevel J, Dijkshoorn L (2006) Adherence of Acinetobacter baumannii strains to human bronchial epithelial cells. Res Microbiol 157:360–366. https://doi.org/10.1016/j.resmic.2005.09.011 PubMed DOI

Morris FC, Dexter C, Kostoulias X, Uddin MI, Peleg AY (2019) The mechanisms of disease caused by Acinetobacter baumannii. Front Microbiol 10:1601. https://doi.org/10.3389/fmicb.2019.01601 PubMed DOI PMC

Naghipour Erami A, Rasooli I, Jahangiri A, Darvish Alipour Astaneh S (2021) Anti-Omp34 antibodies protect against Acinetobacter baumannii in a murine sepsis model. Microb Pathogenesis 161:105291. https://doi.org/10.1016/j.micpath.2021.105291 DOI

Panneerselvam C, Alalawy AI, Albalawi K, Al-Shehri HS, Parveen H, Al-Aoh HA, Bedowr NS, Mujammami FJ, Nusari M, Khateeb S (2022) Anticancer activity of bioactive compound chavicol as potential toxic against human lung cancer A549 cells. J Drug Deliv Sci Tec 73:103442. https://doi.org/10.1016/j.jddst.2022.103442 DOI

Parra-Millán R, Guerrero-Gómez D, Ayerbe-Algaba R, Pachón-Ibáñez ME, Miranda-Vizuete A, Pachón J, Smani Y (2018) Intracellular trafficking and persistence of Acinetobacter baumannii requires transcription factor EB. Msphere 3:e00106-00118. https://doi.org/10.1128/msphere.00106-18 PubMed DOI PMC

Petersen K, Riddle MS, Danko JR, Blazes DL, Hayden R, Tasker SA, Dunne JR (2007) Trauma-related infections in battlefield casualties from Iraq. Ann Surg 245:803. https://doi.org/10.1097/01.sla.0000251707.32332.c1 PubMed DOI PMC

Rumbo C, Tomás M, Fernandez Moreira E, Soares NC, Carvajal M, Santillana E, Beceiro A, Romero A, Bou G (2014) The Acinetobacter baumannii Omp33–36 porin is a virulence factor that induces apoptosis and modulates autophagy in human cells. Infect Immun 82:4666–4680. https://doi.org/10.1128/iai.02034-14 PubMed DOI PMC

Rumbo C, Tomás M, Moreira EF, Soares NC, Carvajal M, Santillana E, Beceiro A, Romero A, Bou G (2014) The Acinetobacter baumannii Omp33–36 porin is a virulence factor that induces apoptosis and modulates autophagy in human cells. Infect Immun 82:4666–4680. https://doi.org/10.1128/iai.02034-14 PubMed DOI PMC

Segura I, Casadesús J, Ramos-Morales F (2004) Use of mixed infections to study cell invasion and intracellular proliferation of Salmonella enterica in eukaryotic cell cultures. J Microbiol Meth 56:83–91. https://doi.org/10.1016/j.mimet.2003.09.004 DOI

She P, Chen L, Qi Y, Xu H, Liu Y, Wang Y, Luo Z, Wu Y (2016) Effects of human serum and apo-Transferrin on Staphylococcus epidermidis RP62A biofilm formation. MicrobiologyOpen 5:957–966. https://doi.org/10.1002/mbo3.379 PubMed DOI PMC

Smani Y, Dominguez-Herrera J, Pachón J (2013) Association of the outer membrane protein Omp33 with fitness and virulence of Acinetobacter baumannii. J Infect Dis 208:1561–1570. https://doi.org/10.1093/infdis/jit386 PubMed DOI