Swine dysentery (SD) is a major concern for pig farmers worldwide. SD prevention relies solely on biosafety measures and prophylactic use of growth promoters, which contain low dosages of antibiotics. With the global awareness towards the conscious use of antimicrobials this practice is gradually being discouraged, and cases of SD started to re-emerge. In this sense, a robust but underexplored research tool might be employed: the in vitro organ culture (IVOC). Many recent studies were published in the last decades using this approach with impactful results, although Brazilian institutions have not disseminated this practice yet. Amongst the reasons for that are: the high cost of implementation, specialized equipment and refined techniques which require personnel training. Accordingly, the present study had the objective of (1) adapting an already existing IVOC colon culturing method to be accessible for most Brazilian laboratories, and to (2) seek for unique characteristics of pathogenic strains of Brachyspira hyodysenteriae which could direct further studies at the pathogenesis of SD. A total of 480 explants were cultured using the adapted IVOC technique and divided into 4 experimental groups: negative control (PBS), B. hyodysenteriae highly pathogenic strain (B_High), B. hyodysenteriae low pathogenic strain (B_Low) and positive control (LPS). 160 out of 480 explants were submitted for qPCR analysis of the TFF3 gene, a marker of acute intestinal inflammation. The remaining 320 explants were submitted for histopathological processing and morphological analysis of parameters such as crypt necrosis and explant survival. Technique standardization results have shown that the adaptations made to the original protocol caused reduced explants survival, which have not impaired the use of the technique. It was found that the adapted method of IVOC for swine colon explants is suited for reproduction in research laboratories for similar research purposes to this study, although the use of KGM media and conditioned media are recommended if higher epithelial cover or longer time in culture is required. At the SD trial was observed an increased gene expression of TFF3 at both B_High and LPS infected groups (0.7 ±0.19 and 0.6 ±0.23 respectively) in comparison to explants from the negative control and B_Low groups. B_High and LPS treated groups have also shown reduced explant survival (B_High: 0.47 ±0.13; LPS: 0.27 ±0.11) and reduced goblet cell abundance (0.29 ±0.11 and 0,28 ±0.10 respectively) compared with both PBS and B_Low groups. Assembling our data, it was possible to suggest that the increased TFF3 gene expression signaled the activation of the wound-healing mechanism and the release of mucins. This innovative link between TFF and B. hyodysenteriae infection can be used as lead in further investigation of SD pathogenesis.

Keywords: in vitro colon culture, swine dysentery, trefoil factors, gene expression, histopathology.