title: Evidence of Bacteroides fragilis protection from Bartonella henselae-induced damage.
abstract: Bartonella henselae is able to internalize endothelial progenitor cells (EPCs), which are resistant to the infection of other common pathogens. Bacteroides fragilis is a gram-negative anaerobe belonging to the gut microflora. It protects from experimental colitis induced by Helicobacter hepaticus through the polysaccharide A (PSA). The aim of our study was to establish: 1) whether B. fragilis colonization could protect from B. henselae infection; if this event may have beneficial effects on EPCs, vascular system and tissues. Our in vitro results establish for the first time that B. fragilis can internalize EPCs and competes with B. henselae during coinfection. We observed a marked activation of the inflammatory response by Real-time PCR and ELISA in coinfected cells compared to B. henselae-infected cells (63 vs 23 up-regulated genes), and after EPCs infection with mutant B. fragilis ΔPSA (≅90% up-regulated genes) compared to B. fragilis. Interestingly, in a mouse model of coinfection, morphological and ultrastructural analyses by hematoxylin-eosin staining and electron microscopy on murine tissues revealed that damages induced by B. henselae can be prevented in the coinfection with B. fragilis but not with its mutant B. fragilis ΔPSA. Moreover, immunohistochemistry analysis with anti-Bartonella showed that the number of positive cells per field decreased of at least 50% in the liver (20±4 vs 50±8), aorta (5±1 vs 10±2) and spleen (25±3 vs 40±6) sections of mice coinfected compared to mice infected only with B. henselae. This decrease was less evident in the coinfection with ΔPSA strain (35±6 in the liver, 5±1 in the aorta and 30±5 in the spleen). Finally, B. fragilis colonization was also able to restore the EPC decrease observed in mice infected with B. henselae (0.65 vs 0.06 media). Thus, our data establish that B. fragilis colonization is able to prevent B. henselae damages through PSA.
authors.affiliation: Division of Immunohematology, Transfusion Medicine and Transplant Immunology, Regional Reference Laboratory of Transplant Immunology, Azienda Universitaria Policlinico, 1st School of Medicine, Second University of Naples, Naples, Italy.
authors.forename: Linda
authors.initials: L
authors.lastname: Sommese
authors.forename: Chiara
authors.initials: C
authors.lastname: Pagliuca
authors.forename: Bice
authors.initials: B
authors.lastname: Avallone
authors.forename: Rossana
authors.initials: R
authors.lastname: Ippolito
authors.forename: Amelia
authors.initials: A
authors.lastname: Casamassimi
authors.forename: Valerio
authors.initials: V
authors.lastname: Costa
authors.forename: Roberta
authors.initials: R
authors.lastname: Colicchio
authors.forename: Raimondo
authors.initials: R
authors.lastname: Cerciello
authors.forename: Maria
authors.initials: M
authors.lastname: D'Armiento
authors.forename: Margherita
authors.initials: M
authors.lastname: Scarpato
authors.forename: Alfonso
authors.initials: A
authors.lastname: Giovane
authors.forename: Gabiria
authors.initials: G
authors.lastname: Pastore
authors.forename: Teresa
authors.initials: T
authors.lastname: Infante
authors.forename: Alfredo
authors.initials: A
authors.lastname: Ciccodicola
authors.forename: Carmela
authors.initials: C
authors.lastname: Fiorito
authors.forename: Francesco Paolo
authors.initials: FP
authors.lastname: D'Armiento
authors.forename: Paola
authors.initials: P
authors.lastname: Salvatore
authors.forename: Claudio
authors.initials: C
authors.lastname: Napoli
mesh_terms: D016917:Angiomatosis, Bacillary / Q000235:genetics / Q000382:microbiology* / Q000473:pathology; D000818:Animals; D000898:Antibiosis; D001442:Bacteroides Infections / Q000235:genetics / Q000382:microbiology* / Q000473:pathology; D001441:Bacteroides fragilis / Q000502:physiology*; D018416:Bartonella henselae / Q000502:physiology*; D016000:Cluster Analysis; D060085:Coinfection; D016207:Cytokines / Q000235:genetics; D004195:Disease Models, Animal; D042783:Endothelial Cells / Q000382:microbiology; D005260:Female; D020869:Gene Expression Profiling; D054884:Host-Pathogen Interactions; D006801:Humans; D007249:Inflammation / Q000235:genetics / Q000382:microbiology; D051379:Mice; D011135:Polysaccharides, Bacterial; D013234:Stem Cells / Q000382:microbiology
chemical_list: D016207:Cytokines; D011135:Polysaccharides, Bacterial