The microbial community that inhabits the enteric tract, the gut microbiota, plays an increasingly significant role in human health. Known by most as “intestinal bacterial flora” it is formed mainly by non-pathogenic bacterial able to perform important functions and interact with our organism. A heterogeneous microbiota qualitatively and quantitatively rich allows to reach conditions of intestinal eubiosis therefore to determine the physio-metabolic well-being of the organism. The enteric colonization begins in every subject from the moment of the delivery therefore it is false to affirm that the intestine of the newborn is germ free: the human vaginal microbiota (VMB) is the first environment with whom the unborn comes in contact and whose it is contaminated. Although the vaginal microbiota is mainly formed by Lactobacillus, the states of the vaginal mucosa community differ by the subspecies of Lactobacilli whose they are composed. Eutocytic delivery exposes the newborn to an average of 109 bacteria per gram of vaginal secretions, leading to a first immunization in the baby. It is clear that children born with caesarean section (C-section) host a more homogeneous and less diversified microbiota. This reason has prompted scholars and therefore doctors to resort to the postnatal sowing of vaginal strains in infants undergoing dystopian childbirth with satisfactory results. It is essential consider the behaviour of childbirth assistants who must try to minimize external interventions. The type of birth also influences the type of milky feeding in the newborn: the vaginal birth in fact facilitates breastfeeding, which is more difficult (50% of cases) in the caesarean sections. The immune cells, Iga-S, human milk oligosaccharides (HMOs), -lactoalbumin, lactoferrin and probiotics of breast milk, through synergistic action are able to passively immunize the infant. With breast-feeding Bifidobacteria and Lattobacilli prevail, on the contrary, through feeding with artificial formulas is greater the presence of Clostridium. The formation of the neonatal intestinal microbiota is then influenced, starting from the sixth month of life, by the type of complementary feeding to the milky one. With the weaning in fact, solid foods are introduced gradually in order to follow the slow physiological growth of the child and satisfy its nutritional needs. Environmental factors, such as sterility or non-sterility of the delivery room and intensive neonatal therapies, and exposure to domestic animals in childhood, are determinants of the maturation of the gut microbiota. The close interconnection and two-way communication between the enteric nervous system (ENS) and the central nervous system (CNS) determines the brain-gut axis. The myenteric plexus and the submucosal plexus interact with the neurons of the CNS with each other through numerous neurotransmitters. Considering this close relationship it is easy to deduce how psycho-social factors are influential on the onset of functional gastrointestinal disorders (FGID) and vice versa, which is why stressogenic events at an early age are responsible for changes in the childhood intestinal microbiota. It is also involved in the defense function of the organism, for example by modulating the action of immune cells or by acting with competitive antagonism with pathogens. To rebalance the intestinal flora in cases of infantile dysbiosis are used probiotics, prebiotics and combinations of them, therefore symbiotic are used. Postbiotics are emerging as a promising therapeutic strategy in the prevention and treatment of necrotizing enterocolitis (NEC), a frequent condition in preterm births. Although their effectiveness has increasingly been proven, considering the interindividual variability of the gut microbiota, further research and testing are needed to make these metabolites safe and therefore easily usable in all pediatric pathological subjects.
La comunità microbica che abita il tratto enterico, ovvero il microbiota intestinale, assume un ruolo sempre più significativo riguardo la salute umana. Conosciuta dai più come “flora batterica intestinale” è formata principalmente da batteri non patogeni in grado di svolgere importanti funzioni ed interagire con il nostro organismo. Un microbiota eterogeneo qualitativamente e ricco quantitativamente permette di raggiungere condizioni di eubiosi intestinale che determinano il benessere fisio-metabolico dell’organismo. La colonizzazione enterica ha inizio sin dal momento del parto, dunque è falso affermare che l’intestino del neonato sia germ free: il microbiota vaginale umano (VMB) è il primo ambiente con cui il nascituro entra in contatto e di cui si contamina. Nonostante il microbiota vaginale sia principalmente formato da Lactobacillus, gli stati di comunità della mucosa vaginale si differenziano per la sottospecie di Lattobacilli di cui sono composti. Il parto eutocico espone il neonato in media fino a 10^9 batteri per grammo di secrezioni vaginali, determinando dunque una prima immunizzazione nel bambino. È chiaro come i bambini invece nati con taglio cesareo ospitino un microbiota più omogeneo e meno diversificato. Questo motivo ha spinto gli studiosi e i medici a ricorrere alla semina postnatale di ceppi vaginali nei neonati sottoposti a parto distocico con risultati soddisfacenti. Il tipo di nascita influenza anche il tipo di alimentazione lattea nel neonato: la nascita vaginale infatti facilita l’allattamento al seno, ciò che invece accade più difficilmente nei parti cesarei. Le cellule immunitarie, le IgA-S, gli oligosaccaridi del latte umano (HMO), l’-lattoalbumina, la lattoferrina e i probiotici del latte materno, tramite azione sinergica sono in grado di immunizzare passivamente il lattante. Con l’allattamento al seno prevalgono Bifidobatteri e Lattobacilli, al contrario, tramite alimentazione con formule artificiali è maggiore la presenza di Clostridium. La formazione del microbiota intestinale viene influenzata, a partire dal 6° mese di vita, dal tipo di alimentazione complementare a quella lattea. Con lo svezzamento infatti si introducono gradualmente cibi solidi al fine di seguire la lenta crescita fisiologica del bambino e soddisfarne i bisogni nutrizionali. Oltre a fattori ambientali, quali la sterilità o meno della sala parto e delle terapie intensive neonatali, anche l’esposizione ad animali domestici in età infantile, sono determinanti della maturazione del microbiota intestinale. La stretta interconnessione e la comunicazione bidirezionale tra il sistema nervoso enterico (SNE) e il sistema nervoso centrale (SNC) determinano il brain-gut axis. Il plesso mioenterico e quello sottomucoso interagiscono con i neuroni del SNC tra loro tramite numerosi neurotrasmettitori. Data questa relazione è facile dedurre come fattori psico-sociali siano influenti sull’insorgenza di disturbi funzionali gastrointestinali (DFGI) e viceversa, motivo per cui eventi stressogeni in età precoce sono responsabili di modificazioni del microbiota intestinale. Esso è inoltre coinvolto nella funzione di difesa dell’organismo andando per esempio a modulare l’azione delle cellule immunitarie o agendo con antagonismo competitivo con i patogeni. Per riequilibrare la flora intestinale in casi di disbiosi infantile si utilizzano probiotici, prebiotici e combinazioni di essi, dunque simbiotici. I postbiotici stanno emergendo come strategia terapeutica promettente nella prevenzione e cura della enterocolite necrotizzante (NEC), patologia frequente nei nati pretermine. Sebbene la loro efficacia sia sempre più provata, data la variabilità interindividuale del microbiota, sono necessarie ulteriori ricerche per rendere questi metaboliti sicuri, dunque facilmente utilizzabili in tutti i soggetti pediatrici patologici.
Sviluppo del microbiota intestinale nel neonato: qual è la reale efficacia di probiotici, prebiotici e postbiotici nel trattamento delle disbiosi intestinali?
POLI, LAURA
2019/2020
Abstract
The microbial community that inhabits the enteric tract, the gut microbiota, plays an increasingly significant role in human health. Known by most as “intestinal bacterial flora” it is formed mainly by non-pathogenic bacterial able to perform important functions and interact with our organism. A heterogeneous microbiota qualitatively and quantitatively rich allows to reach conditions of intestinal eubiosis therefore to determine the physio-metabolic well-being of the organism. The enteric colonization begins in every subject from the moment of the delivery therefore it is false to affirm that the intestine of the newborn is germ free: the human vaginal microbiota (VMB) is the first environment with whom the unborn comes in contact and whose it is contaminated. Although the vaginal microbiota is mainly formed by Lactobacillus, the states of the vaginal mucosa community differ by the subspecies of Lactobacilli whose they are composed. Eutocytic delivery exposes the newborn to an average of 109 bacteria per gram of vaginal secretions, leading to a first immunization in the baby. It is clear that children born with caesarean section (C-section) host a more homogeneous and less diversified microbiota. This reason has prompted scholars and therefore doctors to resort to the postnatal sowing of vaginal strains in infants undergoing dystopian childbirth with satisfactory results. It is essential consider the behaviour of childbirth assistants who must try to minimize external interventions. The type of birth also influences the type of milky feeding in the newborn: the vaginal birth in fact facilitates breastfeeding, which is more difficult (50% of cases) in the caesarean sections. The immune cells, Iga-S, human milk oligosaccharides (HMOs), -lactoalbumin, lactoferrin and probiotics of breast milk, through synergistic action are able to passively immunize the infant. With breast-feeding Bifidobacteria and Lattobacilli prevail, on the contrary, through feeding with artificial formulas is greater the presence of Clostridium. The formation of the neonatal intestinal microbiota is then influenced, starting from the sixth month of life, by the type of complementary feeding to the milky one. With the weaning in fact, solid foods are introduced gradually in order to follow the slow physiological growth of the child and satisfy its nutritional needs. Environmental factors, such as sterility or non-sterility of the delivery room and intensive neonatal therapies, and exposure to domestic animals in childhood, are determinants of the maturation of the gut microbiota. The close interconnection and two-way communication between the enteric nervous system (ENS) and the central nervous system (CNS) determines the brain-gut axis. The myenteric plexus and the submucosal plexus interact with the neurons of the CNS with each other through numerous neurotransmitters. Considering this close relationship it is easy to deduce how psycho-social factors are influential on the onset of functional gastrointestinal disorders (FGID) and vice versa, which is why stressogenic events at an early age are responsible for changes in the childhood intestinal microbiota. It is also involved in the defense function of the organism, for example by modulating the action of immune cells or by acting with competitive antagonism with pathogens. To rebalance the intestinal flora in cases of infantile dysbiosis are used probiotics, prebiotics and combinations of them, therefore symbiotic are used. Postbiotics are emerging as a promising therapeutic strategy in the prevention and treatment of necrotizing enterocolitis (NEC), a frequent condition in preterm births. Although their effectiveness has increasingly been proven, considering the interindividual variability of the gut microbiota, further research and testing are needed to make these metabolites safe and therefore easily usable in all pediatric pathological subjects.È consentito all'utente scaricare e condividere i documenti disponibili a testo pieno in UNITESI UNIPV nel rispetto della licenza Creative Commons del tipo CC BY NC ND.
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https://hdl.handle.net/20.500.14239/12191