AB0164 NON-TUBERCULOSIS MYCOBACTERIA-INDUCED NETosis AND AUTOANTIBODY DYNAMICS IN NTM INFECTION: A COMPARATIVE STUDY WITH PULMONARY TUBERCULOSIS

Background:

Infection-related NETosis products, including DNA and citrullinated antigens, may contribute to the development of autoimmune diseases such as Sjogren's syndrome. While non-tuberculosis mycobacteria (NTM) has been reported to induce NETosis similar to tuberculosis, the relationship between pathogenic autoantibodies and NETosis due to NTM remains underexplored.

Objectives:

We hypothesized that NTM could induce circulating NETosis products akin to pulmonary tuberculosis (Mtb), and sought to determine whether NTM-infected hosts with dynamic pathogenic antibody elevation were linked to higher NETosis biomarkers.

Methods:

Plasma myeloperoxidase (MPO)-DNA detection was performed by sandwich ELISA on individuals with NTM infection at diagnosis and 24 weeks post-antibiotic treatment at the National Taiwan University Hospital. Additionally, treatment-naïve patients diagnosed with Mtb and healthy controls (HC) were recruited for comparison. Anti-dsDNA, anti-ENA (extractable nuclear antigens including RNP, Sm, SS-A(Ro), SS-B(La), Scl-70, and Jo-1), anti-cardiolipin IgG/IgM, and β2-glycoprotein I IgG/IgM titers were assessed using the ELISA method before and six months after NTM pulmonary disease follow-up. The Area Under Curve (AUC) of MPO-DNA was calculated for NTM groups to investigate the impact of NETosis on autoantibody elevation.

Results:

The MPO-DNA value in NTM patients (1.11±1.11 normalized O.D. 450 nm, n=40) was significantly higher than that of HC (0.11±0.17, n=11, p=0.01, U test) and the Mtb group (n=13, p=0.03, U test) (Figure 1). The NETosis marker, MPO-DNA of non-tuberculous mycobacteria, was higher than that of HC and patients with Mtb infection. No significant difference was observed between Mtb infection patients (0.36±0.52, n=13) and the HC group (U test p=0.26). Thirteen individuals from the Mtb group and 11 from the NTM group underwent serial plasma MPO-DNA testing before and 24 weeks after treatment, as illustrated in Figure 2. Notably, the baseline (blue bar) of Mtb patients was lower but significantly increased after treatment (orange bar), with 61.5% doubling the initial value. In contrast, plasma MPO-DNA in most NTM patients decreased after antibiotic treatment, and none of the 11 cases showed a twofold increase. A preliminary definition identified a 2.0 unit/ml elevation in any of the mentioned autoantibodies as "flares of autoimmunity." Among the nine cohorts, three patients experiencing flares (33.3%) displayed a greater Area Under Curve (AUC) of MPO-DNA, the NETs marker (2.65±0.36 vs. 1.78±1.06 O.D.*time periods, p=0.11), in comparison to those without a defined status of autoimmunity flares, although statistical significance was not achieved.

Conclusion:

The MPO-DNA value in NTM patients was significantly higher than that in healthy subjects and the Mtb group. A significant increase in MPO-DNA was observed after treatment in Mtb patients but not in NTM patients. NTM-related NETosis products may offer a mechanism for inducing pathogenic autoantibodies. Individuals with a constellation of elevated autoantibodies were associated with cumulative NETosis product persistence.

REFERENCES:

[1] J Transl Autoimmun. 2021 Feb 5:4:100085 [2] Sci Rep. 2022 Apr 11;12(1):5181. [3] Nat Commun. 2020 Nov 4;11(1):5566. [4] Eur Respir Rev. 2022 Feb 22;31(163):210241. [5] Clin Respir J. 2014 Apr;8(2):137-44.

Acknowledgements:

NIL.

Disclosure of Interests:

Zhi-yun Lai: None declared, Yu-Min Kuo Novartis(only in 2021), Song-Chou Hsieh: None declared, Chiau-jing Jung: None declared, Chin-Chung Shu: None declared.