Evaluating gene expression and biomarkers for mastitis resistance in Barki sheep

Abstract

The aim of this study was monitoring health status of mastitic Barki ewes using candidate gene approach, gene expression and serum profile of inflammatory and antioxidant markers. A total of 70 ewes were allocated into two equal-sized groups: healthy and ewes have a history of mastitis. DNA sequencing of IFN-γ (365-bp), IL-4 (285-bp), TNF-α (273-bp), MYD88 (660-bp), CCL5 (360-bp), TLR4 (256-bp), TLR9 (414-bp), LTF (299-bp), PRLR (891-bp), CAT (300-bp), GPX1 (221-bp), Keap1 (360-bp), OXSR1 (357-bp), ATOX1 (433-bp), GST (480-bp) and Nrf2 (340-bp) revealed single nucleotide polymorphisms (SNPs) between healthy and mastitic ewes. Levels of IFN-γ, IL-4, TNF-α, MYD88, CCL5, TLR4, TLR9, LTF, PRLR, Keap1 and OXSR1 genes expression were significantly up-regulated in ewes affected with mastitis than resistant ones. Meanwhile CAT, GPX1, ATOX1, GST, and Nrf2 genes elicited an opposite trend. There is a significant elevation of activity of AST, LDH, Hp, CP, SAA, IgG, MDA, and NO levels (P < 0.05), along with reduction of total protein, albumin, GSH, GPx, catalase and SOD (P < 0.05) in mastitic ewes. The findings of this study supported the hypothesis that SNPs in immune and antioxidant genes could be important genetic markers for mastitis susceptibility or resistance in Barki ewes. The examined genes' gene expression profiles may also be utilized as surrogate biomarkers to establish an efficient management regimen and forecast the period of time at which a disease is most likely to manifest.

Keywords: Antioxidants; Barki sheep; Gene expression; Immunity; Mastitis; Single nucleotide polymorphisms.

Fig. 1

Relative expression patterns of immunity genes in the healthy and mastitis affected Barki ewes. Results are expressed as means ± SEM. *P < 0.05. IFN-γ interferon gamma, IL-4 iterleukin-4, TNF-α tumor necrosis factor-alpha, MYD88 myeloid differentiation primary response 88, CCL5 chemokine (C-C motif) ligand 5, TLR4 toll-like receptor 4, TLR9 toll-like receptor 9, LTF lactoferrin, PRLR prolactin receptor.

Fig. 2

Relative expression patterns of antioxidant genes in the healthy and mastitis affected Barki ewes. Results are expressed as means ± SEM. *P < 0.05. CAT catalase, GPX1 glutathione peroxidase 1, Keap1 Kelch-like ECH-associated protein 1, OXSR1 oxidative stress responsive kinase 1, ATOX1 antioxidant 1 copper chaperone 1, GST glutathione S transferase, Nrf2 nuclear factor-erythroid factor 2-related factor.

Fig. 3

Correlation between mRNA levels and serum profile of immune and antioxidant markers in mastitis affected Barki ewes. IFN-γ interferon gamma, TNF-α tumor necrosis factor-alpha, LTF lactoferrin, CAT catalase, OXSR1 oxidative stress responsive kinase 1, Nrf2 nuclear factor-erythroid factor 2-related factor.