engBellés, A.Aguirre-Ramírez, D.Abad, I.Sánchez, L.Grasa, L.Native and saturated bovine lactoferrin modulate the expression of toll-like receptors (TLRS) in mice treated with antibiotics. P0203. 29th United European Gastroenterology Week Virtual 2021ART-2021-125001Introduction: The gut microbiota plays a fundamental role in protection against pathogen infections but also in the regulation of the immune sys-tem. The antibiotic administration can result in gut microbiota alterations and changes in the eectiveness of innate immune responses. As micro-biota composition changes, the altered community will present dierent microbial-associated molecular patterns to Toll-like receptors (TLRs), which can cascade down through various immune responses, including changes in the expression of TLR receptors [1]. In this context, finding ingredients that can modulate the immune system is becoming a major focus of interest to produce functional foods. Bovine lactoferrin is a milk protein with many biological properties, including an-tibacterial and immunomodulatory activity [2].Aims & Methods: The objective was to determine the eects of native (nLf) and saturated (sLf) bovine lactoferrin on TLR receptor expression of colon from mice treated or untreated with the antibiotic clindamycin, to evalu-ate its potential to be added in functional foods.Male C57BL/6 mice of 8 weeks old were randomly divided into six groups (n=5 per group): vehicle, clindamycin (Clin), native bovine lactoferrin (nLf), nLf + clindamycin (nLf_Clin), iron-saturated bovine lactoferrin (sLf) and sLf + clindamycin (sLf_Clin). Vehicle received saline orally for 10 days. Clin was gavaged for 10 days with saline and on day 4 received a single IP injection of 200 µg of clindamycin. nLf and sLf were gavaged for 10 days with 35 mg of nLf or sLf. The groups nLf_Clin and sLf_Clin were gavaged with nLf or sLf and on day 4 received an injection of clindamycin.The gene expression (mRNA) of TLR1-9 receptors was determined in the colon from mice by RT-PCR and relative expression levels of genes were calculated using the 2 -∆∆CT method.Results: The expression of TLR2, TLR4, TLR5 and TLR6 was not modified in any of the treated groups. The expression of TLR1 was increased in sLf, nLf_Clin and sLf_Clin treated groups, indicating that the eect of sLf on TLR1 expression was maintained despite the treatment with Clin. The expression of TLR8 and TLR9 decreased in Clin, nLf and nLf_Clin groups. However, the levels of these receptors in sLf_Clin were similar to Vehicle, demonstrating the immunomodulatory capacity of sLf to restore these receptor levels, in a situation of intestinal dysbiosis. Finally, respect to TLR3 and TLR7, only the group of mice treated with sLf_Clin showed an increase in the expression of this receptor. Conclusion: Saturated bovine lactoferrin can restore the expression levels of TLR8 and TLR9 in conditions of intestinal dysbiosis induced by antibiot-ics. These results confirm the immunomodulatory properties of lactoferrin, which have great interest for the design of functional foods.2021http://zaguan.unizar.es/record/108430http://zaguan.unizar.es/record/108430oai:zaguan.unizar.es:108430United European Gastroenterology Journal 9, 58 (2021), 376byhttp://creativecommons.org/licenses/by/3.0/es/info:eu-repo/semantics/openAccess