Celiac disease-associated Neisseria flavescens decreases mitochondrial respiration in CaCo-2 epithelial cells: Impact of Lactobacillus paracasei CBA L74 on bacterial-induced cellular imbalance

: We previously identified a Neisseria flavescens strain in the duodenum of celiac disease (CD) patients that induced immune inflammation in ex vivo duodenal mucosal explants and in CaCo-2 cells. We also found that vesicular trafficking was delayed after the CD-immunogenic P31-43 gliadin peptide-entered CaCo-2 cells and that Lactobacillus paracasei CBA L74 (L. paracasei-CBA) supernatant reduced peptide entry. In this study, we evaluated if metabolism and trafficking was altered in CD-N. flavescens-infected CaCo-2 cells and if any alteration could be mitigated by pretreating cells with L. paracasei-CBA supernatant, despite the presence of P31-43. We measured CaCo-2 bioenergetics by an extracellular flux analyser, N. flavescens and P31-43 intracellular trafficking by immunofluorescence, cellular stress by TBARS assay, and ATP by bioluminescence. We found that CD-N. flavescens colocalised more than control N. flavescens with early endocytic vesicles and more escaped autophagy thereby surviving longer in infected cells. P31-43 increased colocalisation of N. flavescens with early vesicles. Mitochondrial respiration was lower (P < .05) in CD-N. flavescens-infected cells versus not-treated CaCo-2 cells, whereas pretreatment with L. paracasei-CBA reduced CD-N. flavescens viability and improved cell bioenergetics and trafficking. In conclusion, CD-N. flavescens induces metabolic imbalance in CaCo-2 cells, and the L. paracasei-CBA probiotic could be used to correct CD-associated dysbiosis

Novel Approach for Evaluation of Bacteroides fragilis Protective Role against Bartonella henselae Liver Damage in Immunocompromised Murine Model

Bartonella henselae is a gram-negative facultative intracellular bacterium and is the causative agent of cat-scratch disease. Our previous data have established that Bacteroides fragilis colonization is able to prevent B. henselae damages through the polysaccharide A (PSA) in an experimental murine model. In order to determine whether the PSA is essential for the protection against pathogenic effects of B. henselae in immunocompromised hosts, SCID mice were co-infected with B. fragilis wild type or its mutant B. fragilis 1PSA and the effects of infection on murine tissues have been observed by High-Frequency Ultrasound (HFUS), histopathological examination, and Transmission Electron Microscopy (TEM). For the first time, echostructure, hepatic lobes length, vascular alterations, and indirect signs of hepatic dysfunctions, routinely used as signs of disease in humans, have been analyzed in an immunocompromised murine model. Our findings showed echostructural alterations in all infected mice compared with the Phosphate Buffer Solution (PBS) control group; further, those infected with B. henselae and co-infected with B. henselae/B. fragilis 1PSA presented the major echostructural alterations. Half of the mice infected with B. henselae and all those co-infected with B. henselae/B. fragilis 1PSA have showed an altered hepatic echogenicity compared with the renal cortex. The echogenicity score of co-infected mice with B. henselae/B. fragilis 1PSA differed significantly compared with the PBS control group (p < 0.05). Moreover the inflammation score of the histopathological evaluation was fairly concordant with ultrasound findings. Ultrastructural analysis performed by TEM revealed no significant alterations in liver samples of SCID mice infected with B. fragilis wild type while those infected with B. fragilis 1PSA showed the presence of collagen around the main vessels compared with the PBS control group. The liver samples of mice infected with B. henselae showed macro-areas rich in collagen, stellate cells, and histiocytic cells. Interestingly, our data demonstrated that immunocompromised SCID mice infected with B. henselaeand co-infected with B. henselae/B. fragilis ΔPSA showed the most severe morpho-structural liver damage. In addition, these results suggests that the HFUS together with histopathological evaluation could be considered good imaging approach to evaluate hepatic alterations

Seroprevalence of Bartonella henselae in patients awaiting heart transplant in Southern Italy

Background Bartonella henselae is the etiologic agent of cat-scratch disease. B. henselae infections are responsible for a widening spectrum of human diseases, although often symptomless, ranging from self-limited to life-threatening and show different courses and organ involvement due to the balance between host and pathogen. The role of the host immune response to B. henselae is critical in preventing progression to systemic disease. Indeed in immunocompromised patients, such as solid organ transplant patients, B. henselae results in severe disseminated disease and pathologic vasoproliferation. The purpose of this study was to determine the seroprevalence of B. henselae in patients awaiting heart transplant compared to healthy individuals enrolled in the Regional Reference Laboratory of Transplant Immunology of Second University of Naples. Methods Serum samples of 38 patients awaiting heart transplant in comparison to 50 healthy donors were examined using immunfluorescence assay. Results We found a B. henselae significant antibody positivity rate of 21% in patients awaiting heart transplant ( p = 0.002). There was a positive rate of 8% ( p > 0.05) for immunoglobulin (Ig)M and a significant value of 13% ( p = 0.02) for IgG, whereas controls were negative both for IgM and IgG antibodies against B. henselae . The differences in comorbidity between cases and controls were statistically different (1.41 ± 0.96 vs 0.42 ± 0.32; p = 0.001). Conclusions Although this study was conducted in a small number of patients, we suggest that the identification of these bacteria should be included as a routine screening analysis in pretransplant patients

Impairment of circulating endothelial progenitors in Down syndrome

<p>Abstract</p> <p>Background</p> <p>Pathological angiogenesis represents a critical issue in the progression of many diseases. Down syndrome is postulated to be a systemic anti-angiogenesis disease model, possibly due to increased expression of anti-angiogenic regulators on chromosome 21. The aim of our study was to elucidate some features of circulating endothelial progenitor cells in the context of this syndrome.</p> <p>Methods</p> <p>Circulating endothelial progenitors of Down syndrome affected individuals were isolated, <it>in vitro </it>cultured and analyzed by confocal and transmission electron microscopy. ELISA was performed to measure SDF-1α plasma levels in Down syndrome and euploid individuals. Moreover, qRT-PCR was used to quantify expression levels of <it>CXCL12 </it>gene and of its receptor in progenitor cells. The functional impairment of Down progenitors was evaluated through their susceptibility to hydroperoxide-induced oxidative stress with BODIPY assay and the major vulnerability to the infection with human pathogens. The differential expression of crucial genes in Down progenitor cells was evaluated by microarray analysis.</p> <p>Results</p> <p>We detected a marked decrease of progenitors' number in young Down individuals compared to euploid, cell size increase and some major detrimental morphological changes. Moreover, Down syndrome patients also exhibited decreased SDF-1α plasma levels and their progenitors had a reduced expression of SDF-1α encoding gene and of its membrane receptor. We further demonstrated that their progenitor cells are more susceptible to hydroperoxide-induced oxidative stress and infection with Bartonella henselae. Further, we observed that most of the differentially expressed genes belong to angiogenesis, immune response and inflammation pathways, and that infected progenitors with trisomy 21 have a more pronounced perturbation of immune response genes than infected euploid cells.</p> <p>Conclusions</p> <p>Our data provide evidences for a reduced number and altered morphology of endothelial progenitor cells in Down syndrome, also showing the higher susceptibility to oxidative stress and to pathogen infection compared to euploid cells, thereby confirming the angiogenesis and immune response deficit observed in Down syndrome individuals.</p

Metabolismo intermedio e patogenicità microbica: studio della regolazione e dell’espressione differenziale del gene gdhA, codificante la L-glutammato deidrogenasi NADP-specifica, in isolati clinici di Neisseria meningitidis

Neisseria meningitidis (meningococco) è un batterio a ristretto spettro d’ospite e presenta “stili di vita” alternativi: commensale-patogeno, intracellulare-extracellulare. Un fattore cruciale per tale comportamento risiede nella capacità di sintetizzare ed utilizzare nutrienti essenziali per la propria sopravvivenza nei diversi microambienti dell’ospite durante un naturale ciclo infettivo. Dati di letteratura indicano che gdhA, codificante la L-glutammato deidrogenasi NADP-specifica (NADP-GDH) è tra i 73 geni di N. meningitidis necessari per lo stabilirsi della batteriemia nel modello animale del ratto neonato. Nelle Enterobacteriaceae, gdhA è sotto il controllo di diversi circuiti di regolazione; tra questi, quello meglio caratterizzato è controllato dal regolatore Nac (Nitrogen assimilation control), che reprime la trascrizione del gene gdhA in mezzi poveri di ammonio. A sua volta Nac è sotto il controllo del sistema di regolazione globale Ntr, un sistema a due componenti che utilizza il comune fattore –54 per il trasporto della RNA polimerasi. Nel genere Neisseria, non esistono evidenze sperimentali sulla regolazione di tali sistemi. L’assenza di un fattore -54 in questo genere suggerisce l’esistenza di circuiti alternativi al sistema Ntr ben caratterizzato nelle Enterobacteriaceae. E’ stata, quindi, condotta un’analisi del trascrittoma del meningococco, che ha evidenziato l’espressione differenziale di gdhA in isolati clinici provenienti da malati (ceppi invasivi) e da individui sani (ceppi commensali). In particolare, i ceppi appartenenti alle linee ipervirulente ET-5 (sierogruppo B) e IV-1 (sierogruppo A) presentano elevati livelli di mRNA gdhA-specifico. In tali ceppi gdhA è trascritto a partire da due promotori, gdhA P1 e gdhA P2. In contrasto, nei ceppi che esibiscono bassi livelli di mRNA gdhA-specifico, gdhA P2 è inattivo per effetto dei bassi livelli di espressione di gdhR, un gene regolatore associato a gdhA nella mappa genetica, codificante un membro della famiglia GntR di regolatori batterici helix-turn-helix. Esperimenti di inattivazione genica hanno confermato che GdhR regola positivamente l’attività di gdhA P2; la transattivazione di gdhA P2 da parte di GdhR è massima durante la tarda fase logaritmica nel terreno complesso GC. I mutanti gdhR-difettivi perdono sia la regolazione di gdhA dipendente dalla fase di crescita, che dalla fonte di carbonio (energia); esibiscono, infatti, un difetto di crescita più evidente in un terreno chimicamente definito (MCDA) quando il glucosio è utilizzato come fonte di carbonio invece del lattato in presenza di glutammato. Studi di interazione DNA-proteina hanno dimostrato che il 2-oxoglutarato, un prodotto della reazione catabolica della NADP-GDH, ed un intermedio del ciclo degli acidi tricarbossilici (TCA), inibisce il legame di GdhR al promotore gdhA P2. Nel complesso tali dati indicano che la funzione principale della NADP-GDH sia quella di supportare l’attività del ciclo TCA rifornendolo di 2-oxoglutarato, quando il glutammato è disponibile nell’ambiente. Tale attività enzimatica promuove, pertanto, una stimolazione del metabolismo intermedio, particolarmente quando il glucosio prevale sul lattato come fonte di carboinio. Ciò si traduce in un vantaggio selettivo per i ceppi esprimenti alti livelli di mRNA per gdhA che risultano favoriti nella crescita in alcuni siti anatomici rilevanti per il ciclo infettivo del meningococco, quali il sangue ed il liquido cerebrospinale

CXCR4-CXCL12-Dependent Inflammatory Network and Endothelial Progenitors.

The endothelial progenitor cells (EPCs) are angiogenic cells having properties similar to those of embryonal angioblasts. The number and function of EPCs are affected by a variety of conditions, including cytokines and chemokines, which are pivotal inflammatory signaling molecules. The purpose of this paper is to review current knowledge about the role of these progenitor in different vascular diseases, emphasizing the important biological role played from the CXCR4-CXCL12 axis in the cellular trafficking. Indeed, as described in detail in this review, the CXCR4/CXCL12 interaction produces pleiotropic effects in stem cells and plays a pivotal role in several processes related to development, tissue regeneration and development/progression of malignancies