Comparative Transcriptional Analysis of Human Macrophages Exposed to Animal and Human Isolates of
Mycobacterium avium
Subspecies
paratuberculosis
with Diverse Genotypes
Authors: Motiwala Alifiya S. , Janagama Harish K. , Paustian Michael L. , Zhu Xiaochun , Bannantine John P. , Kapur Vivek , Sreevatsan Srinand 
Published: October 2006

ABSTRACT

Mycobacterium avium
subsp.
paratuberculosis
is the causative agent of Johne's disease in animals and has been hypothesized to be associated with Crohn's disease in humans. Recently,
M. avium
subsp.
paratuberculosis
isolates recovered from Crohn's disease patients were shown to have limited diversity, implying the existence of human disease-associated genotypes and strain sharing with animals (A. H. Ghadiali et al., J. Clin. Microbiol.
42:
5345-5348, 2004). To explore whether these genotypic differences or similarities among human and animal isolates translated to functionally significant attributes such as variance in host preference and/or difference in magnitude of infections, we performed a global scale analysis of
M. avium
subsp.
paratuberculosis
isolates that were representative of different genotypes and host species using DNA microarrays. Genome-wide characterization of the transcriptional changes was carried out using a human monocytic cell line (THP-1 cells) in response to different genotypes of
M. avium
subsp.
paratuberculosis
isolates recovered from various hosts. We identified several differentially expressed genes during early intracellular infection, including those involved in common canonical pathways such as NF-κB, interleukin-6 (IL-6), mitogen-activated protein kinase/extracellular signal-regulated kinase, and Jun N-terminal protein kinase signaling, as well as genes involved in T helper type 1 (Th1) responses (such as CCL5 ligand) and those that encode several proinflammatory cytokines and chemokine receptors. The cattle and human isolates of
M. avium
subsp.
paratuberculosis
, regardless of their short sequence repeat (SSR) genotype, induced similar global gene expression patterns in THP-1 cells. They differentially regulated genes necessary for cell survival without causing major alterations in proinflammatory genes. In contrast, the sheep isolates representing diverse SSR genotypes closely resembled the global gene expression pattern of an
M. avium
subsp.
avium
isolate, and they significantly up-regulated proinflammatory genes related to IL-6, T-cell receptor, B-cell receptor, and death receptor signaling within THP-1 cells. Additionally, we demonstrated consistency among infecting genotypes of
M. avium
subsp.
paratuberculosis
isolated from diverse hosts [cattle (
n
= 2), human (
n
= 3), sheep (
n
= 2), and bison (
n
= 1)] in quantitative reverse transcription-PCR analysis of seven differentially expressed genes. While the levels of expression induced by the bison isolate were different compared with cattle or human isolates, they followed the common anti-inflammatory, antiapoptotic trend. Our data suggest that the macrophage responses to
M. avium
subsp.
paratuberculosis
isolates from cattle and human sources, regardless of genotype, follow a common theme of anti-inflammatory responses, an attribute likely associated with successful infection and persistence. However, these expression patterns differ significantly from those in THP-1 cells infected with sheep isolates of
M. avium
subsp.
paratuberculosis
or the
M. avium
subsp.
avium
isolate. These data provide a transcriptional basis for a variety of pathophysiological changes observed during early stages of infection by different strains of
M. avium
subsp.
paratuberculosis
, a first step in understanding trait-allele association in this economically important disease.