Clinical significance of anti-glycopeptidolipid-core IgA antibodies in patients newly diagnosed with Mycobacterium avium complex lung disease

Beyond Symptoms: Radiologic identification of asymptomatic Mycobacterium avium complex pulmonary infections

BACKGROUND

Although international nontuberculous mycobacterial pulmonary disease (NTM-PD) guidelines highlight symptom presence at diagnosis, the clinical characteristics of asymptomatic Mycobacterium avium complex pulmonary infection (MAC-PI) patients remain understudied. We clarified the clinical characteristics and course of asymptomatic MAC-PI patients.

METHODS

We retrospectively analyzed 200 consecutive patients with MAC-PIs and adequate available data who newly met the microbiological and radiological criteria for NTM-PD at Fukujuji Hospital from January 2018 to June 2020. We compared the clinical characteristics and course of asymptomatic patients with symptomatic patients and evaluated factors influencing treatment initiation through multivariate analysis.

RESULTS

111 patients were symptomatic and 89 were asymptomatic at diagnosis. While the proportion was significantly lower than that in the symptomatic group (28.8 %), 15.7 % of asymptomatic group patients had cavitary lesions (P = 0.042). In the asymptomatic group, treatments were initiated in 38 (42.7 %) patients, and cavitary lesions, a positive acid-fast bacilli smear, and younger age were independent risk factors for treatment initiation. Among 22 (57.9 %) patients who experienced disease progression necessitating treatment during follow-up, 13 (34.2 %) displayed radiological progression without any worsening of symptoms. Agents used for treatment were consistent across the groups, with no significant differences in culture conversion, microbiological recurrence rates, or spontaneous culture conversion rates.

CONCLUSION

Routine health checkups and radiological examinations can detect clinically important MAC-PIs even in the absence of symptoms. Considering that the clinical course of asymptomatic MAC-PI patients is largely similar to that of symptomatic patients, timely and appropriate management and intervention are essential for all MAC-PI patients.

Multiparameter immunoprofiling for the diagnosis and differentiation of progressive versus nonprogressive nontuberculous mycobacterial lung disease-A pilot study

Clinical prediction of nontuberculous mycobacteria lung disease (NTM-LD) progression remains challenging. We aimed to evaluate antigen-specific immunoprofiling utilizing flow cytometry (FC) of activation-induced markers (AIM) and IFN-γ enzyme-linked immune absorbent spot assay (ELISpot) accurately identifies patients with NTM-LD, and differentiate those with progressive from nonprogressive NTM-LD. A Prospective, single-center, and laboratory technician-blinded pilot study was conducted to evaluate the FC and ELISpot based immunoprofiling in patients with NTM-LD (n = 18) and controls (n = 22). Among 18 NTM-LD patients, 10 NTM-LD patients were classified into nonprogressive, and 8 as progressive NTM-LD based on clinical and radiological features. Peripheral blood mononuclear cells were collected from patients with NTM-LD and control subjects with negative QuantiFERON results. After stimulation with purified protein derivative (PPD), mycobacteria-specific peptide pools (MTB300, RD1-peptides), and control antigens, we performed IFN-γ ELISpot and FC AIM assays to access their diagnostic accuracies by receiver operating curve (ROC) analysis across study groups. Patients with NTM-LD had significantly higher percentage of CD4+/CD8+ T-cells co-expressing CD25+CD134+ in response to PPD stimulation, differentiating between NTM-LD and controls. Among patients with NTM-LD, there was a significant difference in CD25+CD134+ co-expression in MTB300-stimulated CD8+ T-cells (p <0.05; AUC-ROC = 0.831; Sensitivity = 75% [95% CI: 34.9-96.8]; Specificity = 90% [95% CI: 55.5-99.7]) between progressors and nonprogressors. Significant differences in the ratios of antigen-specific IFN-γ ELISpot responses were also seen for RD1-nil/PPD-nil and RD1-nil/anti-CD3-nil between patients with nonprogressive vs. progressive NTM-LD. Our results suggest that multiparameter immunoprofiling can accurately identify patients with NTM-LD and may identify patients at risk of disease progression. A larger longitudinal study is needed to further evaluate this novel immunoprofiling approach.

The factors associated with mortality and progressive disease of nontuberculous mycobacterial lung disease: a systematic review and meta-analysis

This systematic review and meta-analysis aimed to comprehensively evaluate the factors associated with mortality and progressive disease in NTM-LD patients. We conducted a literature search to identify the eligible studies, dated between January 1, 2007, and April 12, 2021. Forty-one studies with total 10,452 patients were included. The overall all-cause mortality rate was 20% (95% CI 17-24%). The overall rates of clinical and radiographic progressive disease were 46% (95% CI 39-53%) and 43% (95% CI 31-55%), respectively. Older age, male sex, history of TB, diabetes, chronic heart disease, malignancy, systemic immunosuppression, chronic liver disease, presence of cavity, consolidative radiologic features, acid-fast bacillus (AFB) smear positivity, hypoalbuminemia, anemia, increasing platelet count, high CRP, and high ESR were significantly associated with increased all-cause mortality, whereas increasing body mass index (BMI), hemoptysis, and treatment with rifamycin regimen (in M. xenopi) were significantly associated with decreased all-cause mortality in multivariable analysis. History of TB, Aspergillus co-infection, cough, increased sputum, weight loss, presence of cavity, and AFB smear positivity were significantly associated with increased clinical progression with treatment, while older age and low BMI were significantly associated with decreased clinical progression in multivariable analysis. Older age, interstitial lung disease, presence of cavity, consolidative radiologic feature, anemia, high CRP, and leukocytosis were significantly associated with increased radiographic progression after adjusting for covariates. Older age, history of tuberculosis, presence of cavity, consolidative radiologic features, AFB smear positivity, anemia, and high C-reactive protein were common significant factors associated with the all-cause mortality and clinical or radiographic progressive disease of NTM-LD. These factors are thought to directly affect NTM-LD related mortality. The future prediction models for the prognosis of NTM-LD should be established considering these factors.

Detection of Mycobacterium avium-intracellulare Complex (MAC) by Bronchial Lavage and the Relationship with Titers of Anti-Glycopeptidolipid-Core IgA Antibodies to MAC in Patients with Pulmonary MAC Disease

Background

Higher rates of diagnosis of pulmonary Mycobacterium avium-intracellulare complex (MAC) disease by bronchoscopy (BS) in patients who could not diagnose by sputum cultures have been suggested, but the detailed utility of BS, especially in combination with anti-glycopeptidolipid-core IgA antibodies (anti-MAC Ab), is still unclear.

Methods

A total of 111 patients at our hospital with suspected MAC who underwent BS because they were sputum-negative from April 2018 to March 2022 were analyzed prospectively. These patients were also divided into two groups, anti-MAC Ab-positive and anti-MAC Ab-negative, and compared.

Results

A total of 111 patients underwent BS, though 95 (38.0%) of 250 enrolled patients were sputum smear/culture-positive. The age of the 111 patients was 69.14 (31.0-89.0) years, and 90 (81.0%) were female; 69 (62.2%) of 111 patients were either smear-positive (n = 42, 37.8%) or culture-positive (n = 27, 24.3%) by BS. Of the total 111 patients, 69 (62.2%) were anti-MAC Ab-positive and 57 (82.6%) of 69 patients were also positive by BS. In contrast, only 12 (28.6%) of the 42 anti-MAC Ab-negative patients were positive by BS. The sensitivity and specificity of anti-MAC Ab for positive by BS were 82.6% and 71.4%, respectively, and the area under the curve (AUC) on receiver-operating characteristic (ROC) curve analysis was 0.807.

Conclusion

BS and anti-MAC Ab showed similar usefulness to confirm the diagnosis in patients who could not be diagnosed by sputum examination, but pulmonary MAC disease was strongly suspected based on chest radiography/CT findings. These two examinations were correlated, and their combination appeared to provide more accurate diagnosis and earlier therapy.

Combination of anti-glycopeptidolipid-core IgA antibody and clinical features for diagnosing potential nontuberculous mycobacterium pulmonary disease in routine practice

Background:

The anti- Mycobacterium avium complex (MAC) antibody test measures levels of IgA antibody against the glycopeptidolipid (GPL) core in the bacterial cell walls and is a useful clinical indicator of nontuberculous mycobacterium pulmonary disease (NTM-PD). However, it is not currently possible to diagnose the disease using anti-MAC antibodies alone.

Objectives:

The study aim was to assess the efficacy of the combination of anti-MAC antibodies and clinical findings for diagnosing potential NTM-PD.

Methods:

This cross-sectional study included 938 patients tested using the anti-MAC antibody. NTM-PD was diagnosed by multiple positive cultures of the same species in sputum samples. Multivariate logistic regression models were used to identify the clinical factors related to NTM-PD.

Results:

Overall, 19.6% (184/938) of participants were diagnosed with NTM-PD. In multivariate analysis, positive anti-MAC antibodies, low body mass index, absence of malignancy, and cavity-forming lung lesions were significantly associated with NTM-PD at diagnosis. The positive rates of the anti-MAC antibody test were 79.4% (135/170) for MAC and 55.6% (5/9) for Mycobacterium abscessus complex, respectively.

Conclusions:

Bronchoscopic examinations should be performed especially in certain types of individuals from whom sputum samples cannot be obtained. Anti-MAC antibodies are also positive in patients other than those harboring MAC, but the rate may be low because of the different components in GPLs.

Serum GPL core antibody levels are associated with disease activity and treatment outcomes in Mycobacterium avium complex lung disease following first line antibiotic treatment

BACKGROUND

No objective serum biomarkers of disease course or treatment outcome of Mycobacterium avium complex lung disease (MAC-LD) presently exist. Serum IgA antibody levels against the glycopeptidolipid (GPL) core have good diagnostic accuracy for MAC-LD. However, their usefulness for monitoring and predicting disease course and outcome of MAC-LD following first-line antibiotic treatment remains unclear.

METHODS

We conducted a single-center retrospective cohort study to investigate the utility of serial measurements of GPL core IgA antibodies for monitoring disease course in 133 patients with MAC-LD following first-line antibiotic treatment.

RESULTS

Patients were classified into treatment failure [n = 46 (34.6%)], recurrence [n = 19 (14.3%)], or treatment success [n = 68 (51.1%)] groups according to bacteriological outcomes after chemotherapy. Pretreatment serum anti-GPL core IgA levels in the treatment success group were similar to those in the treatment failure and recurrence groups (P = 0.6431 and P = 0.9045, respectively). In the treatment success group, serum anti-GPL core IgA levels were significantly and continuously reduced after initiating antibiotic treatment. No significant reductions in anti-GPL core IgA levels were observed in either the treatment failure or recurrence groups. Reduced levels of GPL core antibodies following antibiotic treatment correlated well with treatment outcomes (P = 0.0045).

CONCLUSION

In this study, by performing serial measurements, we found that GPL core antibody levels were associated with disease activity and treatment outcomes in patients with MAC-LD. Time course analysis of anti-GPL core IgA levels clearly differentiated between patients who achieved treatment success and those who experienced treatment failure or disease recurrence.