Perfil de expressão de citocinas no trato gastrintestinal de ovinos resistentes e suscetíveis a infecções por nematoides

Abstract

Gastrointestinal nematodes infections cause losses in animal production, especially in sheep farming, an important socioeconomic activity. Undestanding the mechanisms involved in the immune response of these animals to these infections is essential, onceanimals belonging to the same breed and herd respond differently to infections. The lack of studies involving this differentiation in sheep leads to the need to better understand these mechanisms. In this sense the aim of this work was to quantify the expression of cytokines (IFN-γ, TNF-α, IL-4, IL-13, IL-9, IL-22, TGF-β and IL-10) involved in the immune response to gastrointestinal nematodes in sheep phenotypically classified as resistant and susceptible. Abomasum (AB), small (SI) and large intestine (LG) samples from 12 crossbred sheep naturally infected by gastrointestinal nematodes, 6 resistant (RG) and 6 susceptible (SG) animals were used. From these samples, total RNA was isolated from the tissues, cDNA synthesized and quantified by qPCR to determine relative expression, using na ideal reference gene for each tissue (GAPDH, SDHA and RPL-19) and analyzed by REST© software. There was increase in the expression of IL-4 and IL-13 in all tissues of gastrointestinal tract in resistant group to nematode infections compared to animals in the susceptible group. In AB, SI and LG, respectively, there was an increase to 2,5x, 2,8x (p<0,017) and 1,3x to IL-4 and 1,1x, 1,3x and 7,0x (p<0,001) of IL-13. On the other hand, TNF-α and IL-9 were associated with the profile of susceptibility to infection, being more expressed in all gastrointestinal segments of susceptible animals. In this group, AB, SI and LG there was increase of 1,1x, 5,3 (p<0,001) and 2,2x in TNF-α and 2,6x, 1,8x and 1,5x of IL-9. In conclusion, IL-4 and IL-13 were associated with resistance profile and TNFα and IL-9 with susceptibility profile. The expression of the other cytokines varied in the different organs of the different groups, probably due to the dynamic and interation of parasites in each tissue.