THE BACTERIAL FECAL MICROBIOTA OF FOOD-SENSITIZED CHILDREN WITH JUVENILE POLYPS EXHIBITS A DISTINCT COMPOSITION COMPARED TO THAT OF NON-ALLERGIC HEALTHY INDIVIDUALS

MANUELA ILID; JULIAN VACCARO; BELEN POLO; ANABELLA ZOSI; LUCIANA GUZMÁN; CECILIA ZUBIRI; VIVIANA BERNEDO; PAULA BOROBIA; MARCELA ALTAMIRANO; MARCELA GARCIA; RENATA CURCIARELLO; GUILLERMO HORACIO DOCENA; LUIS DIAMBRA; CECILIA ISABEL MUGLIA

San Luis

Congreso; Reunión Anual de Sociedades de Biociencia SAI 2023; 2023

Food allergy is characterized by an immune reaction to foods. We have previously characterized that 90% of children with juvenile colorectal polyp (JCP) from La Plata Children´s Hospital are sensitized to food allergens, JCP showed type 2 inflammation and are active sites of IgE synthesis.It has been reported low levels of gut microbiota diversity in food allergic children, marked by predominance of Firmicutes over Bacteroidetes phylum. Nevertheless, there are no reports regarding microbiota composition associated to JCP. The aim of this work was to characterize bacterial populations in feces and colonic tissue of allergen sensitized children with JCP in comparison to that of healthy children.Stool samples from food-sensitized children (FSC) with JCP (n=11) and non-allergic children (non-FAC) (controls, n=25) were collected. JCP (n=18) and surrounding tissue biopsies (B) (n=7) were obtained by colonoscopy for microbiota analysis. Microbial DNA was extracted using the QIAmp PowerFecal and AIamp Stool DNA kits, respectively. 16S rRNA V3-V4 hypervariable regions were amplified and Illumina sequencing was performed. Sequences were analyzed through Qiime2 software. Amplicon Sequence Variants (ASV) abundance and representative sequences were generated. The Shannon index was used for evaluation of alpha diversity, while Weighted Unifrac was used for beta diversity. The resulting distances were visualized using Principal Coordinate Analysis (PCoA). Finally, a taxonomic analysis was applied where the representative sequences had been assigned taxonomic labels, giving potential identities of the microbial species represented by the ASVs.Whereas alpha diversity showed no significant differences in fecal (p=0.73) or tissue (p=0.89) samples (Kruskal-Wallis), we found beta diversity differences between the fetal microbiota of FSC and non-FAC (p=0.001, PERMANOVA). JCP and B tissues showed no significant differences (p=0.732). PCoA highlighted distinct fecal and tissue sample clustering, while fecal samples could be discerned between FSC and non-FAC samples. The taxonomic analysis of the bacterial communities in samples from FSC and non-FAC showed similar profiles to those reported, with a reduction of Bacteroidetes (Bacteroides) and increase in Firmicutes (Lactobacilleae) phila associated to feces from FSC. Also, we detected the presence of Bifidobacterium bifidum in B but not in JCP, while polyps present an increase in Firmicutes and Clostridium spp. In conclusion, we characterized the fecal and tissue-associated microbiota in children with JCP associated to food allergy and in non-allergic children. This is the first description of microbiota composition of food allergic patients carried out in Argentina and we mainly found food allergy-associated bacterial species in JCP tissues. These findings may pave the way for a more comprehensive understanding of the association between colorectal polyp development and allergy to food antigens.