BACTERIAL FECAL MICROBIOTA OF FOOD SENSITIZED CHILDREN WITH JUVENILE POLYPS PRESENTS A DIFFERENT COMPOSITION SIGNATURE COMPARED TO THAT OF NON-ALLERGIC HEALTHY INDIVIDUALS

MANUELA ILLID; JULIÁN VACCARO; MARIA BELÉN POLO; LORENA MENENDEZ; PAULA BOROBIA; CECILIA ZUBIRI; ANABELLA ZOSI; LUCIANA GUZMÁN; VIVIANA BERNEDO; MARCELA GARCÍA ; RENATA CURCIARELLO; GUILLERMO H. DOCENA; LUIS DIAMBRA; CECILIA I. MUGLIA

San Luis

Congreso; Reunión Anual de la Sociedad Argentina de Inmunología (SAI); 2023

Food allergy is characterized by an immune reaction to foods. We havepreviously characterized that 90% of children with juvenile colorectal polyp(JCP) from La Plata Children's Hospital are sensitized to food allergens, JCPshowed type 2 inflammation and are active sites of IgE synthesis. It has beenreported low levels of gut microbiota diversity in food allergic children, markedby predominance of Firmicutes over Bacteroidetes phylum. Nevertheless, thereare no reports regarding microbiota composition associated to JCP. The aim ofthis work was to characterize bacterial populations in feces and colonic tissue ofallergen sensitized children with JCP in comparison to that of healthy children.Stool samples from food-sensitized children (FSC) with JCP (n=11) and nonallergic children (non-FAC) (controls, n=25) were collected. JCP (n=18) andsurrounding tissue biopsies (B) (n=7) were obtained by colonoscopy formicrobiota analysis. Microbial DNA was extracted using the QIAmp PowerFecaland AIamp Stool DNA kits, respectively. 16S rRNA V3-V4 hypervariable regionswere amplified and Illumina sequencing was performed. Sequences wereanalyzed through Qiime2 software. Amplicon Sequence Variants (ASV)abundance and representative sequences were generated. The Shannon indexwas used for evaluation of alpha diversity, while Weighted Unifrac was used forbeta diversity. The resulting distances were visualized using PrincipalCoordinate Analysis (PCoA). Finally, a taxonomic analysis was applied wherethe representative sequences had been assigned taxonomic labels, givingpotential identities of the microbial species represented by the ASVs.Whereas alpha diversity showed no significant differences in fecal (p=0.73) ortissue (p=0.89) samples (Kruskal-Wallis), we found beta diversity differencesbetween the fetal microbiota of FSC and non-FAC (p=0.001, PERMANOVA).JCP and B tissues showed no significant differences (p=0.732). PCoAhighlighted distinct fecal and tissue sample clustering, while fecal samples couldbe discerned between FSC and non-FAC samples. The taxonomic analysis ofthe bacterial communities in samples from FSC and non-FAC showed similarprofiles to those reported, with a reduction of Bacteroidetes (Bacteroides) andincrease in Firmicutes (Lactobacilleae) phila associated to feces from FSC. Also,we detected the presence of Bifidobacterium bifidum in B but not in JCP, whilepolyps present an increase in Firmicutes and Clostridium spp.In conclusion, we characterized the fecal and tissue-associated microbiota inchildren with JCP associated to food allergy and in non-allergic children. This isthe first description of microbiota composition of food allergic patients carried outin Argentina and we mainly found food allergy-associated bacterial species inJCP tissues. These findings may pave the way for a more comprehensiveunderstanding of the association between colorectal polyp development andallergy to food antigens.