To Set up NTM Stimulation Test Foar Diagnosing NTM Pulmonary Infectionon. Clinical Trial
Official title:
Establishing a Diagnostic Test for Non-tuberculous Mycobacteria Lung Infection Using Non-tuberculous Mycobacteria Antigen Stimulation Test: From Immune Base, Standardized Setup to Validation
1. To compare TLR-2 expression of peripheral blood mononuclear cells and serum downstream
cytokines in those with MAC or MAB pulmonary infection and those with MAC or MAB
pulmonary colonization and controls.
2. To investigate the response of TLR-2 expression and cytokines activation to NTM
stimulation test in patients with MAC or MAB pulmonary infection and colonization and
controls.
3. To validate the NTM stimulation test for NTM pulmonary infection.
The increase of nontuberculous mycobacteria lung infection Nontuberculous mycobacteria lung
infection (NTM-LD) becomes an important clinical concern [1] because the rate of NTM
infection has increased over the past ten years [2-3]. According to a study in Taiwan,
NTM-LD increased from 1.26 to 7.94 per 100,000 inpatients/year during 2000 to 2008 [2]. The
reasons for this increase are not readily clear, but could be related to the growth in
numbers of the acquired immunocompromised population and advances of technique for
mycobacterial culture [4-7]. Among the NTM infection in Taiwan, Mycobacterium avium complex
(MAC) and M. abscessus (MAB) were most frequently isolated [2].
The difficulty in early diagnosing and confirming true NTM-LD However, NTM exists in the
environment ubiquitously, so the relevance (true disease patient number over the number of
patients with disease or just colonization) is far less than 100% and varied in different
NTM species. For example, previous studies have shown that the presence of M. kansasii and
MAC had a clinical relevance around 47~70% and 35~42%, respectively [8-9]. As for MAB which
is emerging pathogen worldwide, has a relevance of 33% [9]. According to contemporary NTM
guidelines established by American thoracic society, NTM pulmonary infection is diagnosed by
multiple criteria including microbiology of respiratory specimen and clinical findings as
well as radiographic findings [1]. In microbiology criteria, two or more sets of positive
sputum mycobacterial culture for the same NTM species within one year is needed.
Because NTM colonization is not uncommon in respiratory tract, diagnosis of true pulmonary
NTM infection is a great challenge in clinical practice. Actually, microbiology tests for
mycobacteria are neither timely nor efficient. Mycobacterial culture is time-consuming,
which needed weeks to wait the results even though it's current gold standard for
micro-organism identification [10]. The nucleic acid amplification method such as polymerase
chain reaction could not discriminate true NTM infection and solely colonization because the
micro-organism is present in both situations [11].
To early diagnose and then start treatment of NTM infection is important because NTM
pulmonary infection might be rapid lethal infection in intensive care unit or in patients
who had not received early proper treatment [6]. In addition, MAC or MAB which are most
common in Taiwan are resistant to most of anti-tuberculosis regimen. Hence, more rapid and
accurate diagnostic test should be developed [1-2, 6] The help of innate immunity in
diagnosing NTM-LD The body inflammatory marker, represent our immune response, would be an
indicator for differentiating true mycobacterial pulmonary infection from colonization while
the first set of mycobacterial culture grew NTM [12-15]. Both interferon-gamma and tumor
necrosis factor-alpha play critical roles in protective immunity to mycobacterial infections
[16-17]. These responses are linked to engagement of Toll-like receptor 2 (TLR2) that is
critical for mycobacterial infection [18]. However, the TLR-2 expression has not been
evaluated between patients with NTM infection and colonization. According to the success of
application of interferon-gamma release assay for tuberculosis detection [19], we understand
the specific immune response is helpful to diagnose mycobacterial infection. We therefore
focus on the expression of TLR-2 and associated downstream cytokines in our patients with
MAC or MAB lung disease, which accounts the most of NTM infection [2].
The design in our study for diagnosis In order to investigate the help of host immune in
diagnosing NTM pulmonary infection, we initially compare the baseline expression of TLR-2
and downstream cytokines in the MAC or MAB infected patients and colonized subjects. Then,
we perform an in-vitro stimulation test using mycobacteria (MAC or MAB) for co-culturing
with peripheral blood mononuclear cells of patients. The TLR-2 expression and cytokines
activation will be examined after the stimulation test. We then analyze the expression
difference between NTM-LD and colonization.
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Observational Model: Case Control, Time Perspective: Prospective