Innate Immune Responses Associated with Resistance against Haemonchus contortus in Morada Nova Sheep

Author(s)

Barbosa Toscano, Joao Henrique ^[1] ; Okino, Cintia Hiromi ^[2] ; dos Santos, Isabella Barbosa ^[1] ; Giraldelo, Luciana Aparecida ^[3] ; von Haehling, Marei Borsch ^[1] ; Esteves, Sergio Novita ^[2] ; de Souza Chagas, Ana Carolina ^[2]

Affiliation

^[1] Univ Estadual Paulista, Fac Ciencias Agr & Vet, Via Acesso Prof Paulo Donato Castellane, BR-14884900 Sao Paulo, SP - Brazil

^[2] Embrapa Pecudria Sudeste, Km 234, Fazenda Canchim 339, BR-13560970 Sao Carlos, SP - Brazil

^[3] Ctr Univ Cent Paulista, Rua Miguel Petroni 5111, BR-13563470 Sao Carlos, SP - Brazil

• Document type: Journal article
• Source: JOURNAL OF IMMUNOLOGY RESEARCH; v. 2019, NOV 11 2019.
• Web of Science Citations: 0

Abstract

The immune response against Haemonchus contortus infections is primarily associated with the Th2 profile. However, the exact mechanisms associated with increased sheep resistance against this parasite remains poorly elucidated. The present study is aimed at evaluating mediators from the innate immune response in lambs of the Morada Nova Brazilian breed with contrasting H. contortus resistance phenotypes. Briefly, 287 lambs were characterized through fecal egg counts (FEC) and packed cell volume (PCV) after two independent experimental parasitic challenges with 4,000 H. contortus L-3. 20 extreme resistance phenotypes (10 most resistant and 10 most susceptible) were selected, subjected to a third artificial infection with 4,000 L-3, and euthanized 7 days later. Tissue samples were collected from abomasal fundic and pyloric mucosa and abomasal lymph nodes. Blood samples were collected at days 0 and 7 of the third parasitic challenge. RNA was extracted from tissue and blood samples for relative quantification of innate immune-related genes by RT-qPCR. For the abomasal fundic mucosa, increased TNF alpha and IL1 beta expression levels (P<0.05) were found in the susceptible animals, while resistant animals had IL33 superiorly expressed (P<0.05). Higher levels (P<0.05) of TLR2 and CFI were found in the abomasal pyloric mucosa of resistant animals. TNF alpha was at higher levels (P<0.05) in the blood of susceptible lambs, at day 0 of the third artificial infection. The exacerbated proinflammatory response observed in susceptible animals, at both local and systemic levels, may be a consequence of high H. contortus parasitism. This hypothesis is corroborated by the higher blood levels of TNF alpha before the onset of infection, which probably remained elevated from the previous parasitic challenges. On the other hand, resistant lambs had an enhanced response mediated by TLR recognition and complement activation. Nevertheless, this is the first study to directly associate sheep parasitic resistance with IL33, an innate trigger of the Th2-polarized response. (AU)

• FAPESP's process: 17/24289-0 - Morada Nova newborns: care after birth, evaluation of levels of infection by gastrointestinal nematodes and its impact on weight gain
• Grantee: Luciana Aparecida Giraldelo
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• FAPESP's process: 17/01626-1 - Genetic and immune responses characterization associated with the phenotype of parasite resistance in a sheep flock of Morada Nova
• Grantee: Ana Carolina de Souza Chagas
• Support Opportunities: Regular Research Grants
• FAPESP's process: 17/00373-2 - Characterization of local immune responses associated with the parasitic resistance phenotype in morada nova lambs
• Grantee: João Henrique Barbosa Toscano
• Support Opportunities: Scholarships in Brazil - Master