Coexpression of NRAMP1, iNOS, and Nitrotyrosine in Bovine Tuberculosis

Abstract

Abstract. In murine models the inducible nitric oxide synthase (iNOS) and the natural resistance associated macrophage protein (NRAMP1) play major roles in host defense against mycobacteria. iNOS regulates nitric oxide (NO) production, which is noxious for ingested mycobacteria, and NRAMP1 displays pleiotropic antimicrobial effects, including upregulation of iNOS expression. Little is known about the role of these molecules in bovine tuberculosis (TB). In this work we demonstrate by Western blot a high expression of NRAMP1 in peripheral blood mononuclear cells (PBMCs), alveolar macrophages (obtained by bronchioalveolar lavage), and lymph node granulomas from 8 HolsteinFreisian cattle with autopsy-proven bovine TB. Immunohistochemistry revealed the abundant expression of NRAMP1 and iNOS in lymph node and lung granulomas. Immunoreactivity was abundant in the cytoplasm of many epithelioid macrophages and multinucleated giant cells of the Langhans type. A striking accumulation of nitrotyrosine (NT), an indicator of iNOS activity and local NO production, was observed in granuloma cells, particularly in multinucleated Langhans cells. This study shows that the expression of NRAMP1 and iNOS is costimulated in granulomas, which are protective T-cell reactions against mycobacteria.

Lesion Development and Immunohistochemical Changes in Granulomas from Cattle Experimentally Infected withMycobacterium bovis

“…10 Recently iNOS expression has been documented in granulomas from cattle naturally infected with M. bovis. 34 Expression varied between cattle, likely due to the unknown duration of infection and stage of granuloma development. In the present study, iNOS immunoreactivity decreased in later stages of II 0 50 88 63 31 33 8 14 III 0 0 11 47 21 22 49 30 IV 0 0 0 16 10 20 20 8 868…”

Relationship of Bovine SLC11A1 (Formerly NRAMP1) Polymorphisms to the Risk of Bovine Tuberculosis in Holstein Cattle

“…Naturally resistant animals had the highest phagocytosis index and showed greater microbial control after exposure to M. bovis stimuli, producing stronger pro-inflammatory responses compared with susceptible animals [23]. In seeking to understand the reasons for natural variation in resistance, a high expression of NRAMP1 in peripheral blood cells and tuberculous granulomas from M. bovisinfected cattle appears to support a functional association for the SLC11A1 gene with enhanced protection against mycobacteria [5,23]. In bovines, two SLC11A1 alleles have been cloned and mapped to chromosome 2q43, which corresponds to a region predicted to encode a transmembrane polypeptide molecule that contains a conserved transporter motif and multiple phosphorylation sites [6,[13][14][15].…”

“…Naturally resistant animals had the highest phagocytosis index and showed greater microbial control after exposure to M. bovis stimuli, producing stronger pro-inflammatory responses compared with susceptible animals [23]. In seeking to understand the reasons for natural variation in resistance, a high expression of NRAMP1 in peripheral blood cells and tuberculous granulomas from M. bovisinfected cattle appears to support a functional association for the SLC11A1 gene with enhanced protection against mycobacteria [5,23].…”

Mycobacterium bovis DNA Detection in Colostrum as a Potential Indicator of Vaccination Effectiveness against Bovine Tuberculosis

“…The protein content of EEP-1 was adjusted to 400 g/ml and mixed with a commercial adjuvant (Polygen; MVP Laboratories, Inc.) to a final concentration of 10% (vol/vol). Protein integrity was checked with SDS-PAGE and Western blotting as described previously (34), using an anti-Mycobacterium tuberculosis polyclonal antibody (ab905; Abcam, Cambridge, MA). EEP-1 mostly contains culture filtrate proteins of Ͻ30 kDa.…”